Sorry for the small mess. I posted the above, but then noticed it could have been made a lot neater.
I started editing it, but didn't know there's a 10min limit for editing. Editing took more than 10mins. So I'll repost in a more organized manner:
Ok, I'll put here a list of unexplained linguistic phenomena I can think of now:
1) the existence of elfdalian (a germanic lgg with 4 cases in the middle of Sweden)
2) the persistence of some languages such as Basque and Maltese
about Basque: why was this the only pre-aryan language to remain in Europe? How come it wasn't crushed in colonizing efforts?
For Maltese, similar question. How come 800 years of European rule were fine with speaking Arabic in the island to this day?
3) the extremely effective linguistic-imperial measures in Brazil.
That is, how come they can make a region the size of Europe have 99+% of whole people speak a single language? As far as I know, this is unique in the world today, as for example Russian has its many Federations inside it, and 25% of the US pop learns Castillian as first language. Maybe China could be similar, proportionally.
4) How did the Brazilians stop speaking the "lingua geral", the indinginous-portuguese mix that's supposed to have lived from the inception of the colony until 1850 here. Supposdely, this Marquis of pombal guy decreed people should speak portuguese, and in 50 years it was said and done in a millions, million and million of square kilometers of a country.
5) If analytical languages could have a different origin as fusional ones, then why are the pronouns usually quite flexional as well? Most romance cases have at least 4 cases in their pronouns (Cast.: el (nom.), lo (acc.), le (dat.), su (gen.))
And why some aryan languages have up to 10 cases, and some have only 4?
Btw, is it a sort of threshold? I don't know about an Aryan langauge that has one 3 cases. It's either 1/2, or 4+
6) I saw the thread here about the cognates in Basque, Etruscan, Minoan. If that's correct, its speaks for itself
7) Why Brazilian Romance especially analytical? probably the most I know. Even if we write in a more flexional matter, we don't speak like that. In Southern urban areas, the less educated somebody is, the more analyitcal they speak. In Northern areas, sometimes it's actually the opposite.
8) Why is Br romance so different from portuguese romance? There are syntactical constructions that are just mutually impossible. And it's easy to hear how they sound different. How come there's not a single place in Br that people speak like portuguese do? How come there's not a single place in portugal that hey speak like Br do?
9) How come there's not A SINGLE place in Br that people speak an African language? It has only been preserved liturgically. I suppose this same question applies to all nations with high level of ex-slave populations.
10) Why were the languages chosen for writing usually fusional instead of analytical?
11) Why was the chronology (according to mainstream academia) usually 700 hundred years from a language starting being written and then "becoming" more analytical?
12) Bulgarian, Macedonian and Romanian share 3 genders (different from other romance language, similar to other Slavic), and a noun in the end of the word. They're neighbors.
13) How come the word for Mother and Father is so similar around the globe? It's not just Ma and pa, it's also Anna and Atta. I'd have to look it up, but from the top of my head, almost 80% of all langauges have a word from Mother that's either Ma or Anna (or slight variations), and for Father pa or Atta (or slight variations).
14) How come different languages from supposedly differing branches have N meaning negation? That's the case of Tokyonese ("Japanese"), Tupi (pre-colombian people in S. America), Aryan Languages, and in Hungarian if I'm not mistaken. I think there are more, that I don't remember.
15) English. Oooooh English. Well, let's open that padonra's box.
First, the pronunciation. It's the only language I know people can't say /e/ and /o/ and /u/ straight, they have to say /ey/ or /ow/ or /uw/
the /r/ is not only retroflex, but it doesn't touch the palate and it's rounded (!?)
at the same time, it has lots of vowels. It's a combination I've never seen of many vowel, but not being able to pronounce some very common vowels, but being able to pronounce uncommon ones.
the phonetics in the end become quite... windy. Speaking English feels like you're taking winds and turns. Very different from speaking Castillian for example.
On that note, I was doing some simple experiments with writing mantras in different languages, and English turned out to be one of the most difficult ones. For prayers or recitations, only rarely it'd more powerful than in other languages. The experiments were rudimentary, and I was going most for feeling and raw output of energy, but I still found it significant.
It has 50% of vocab from latin-romance-greek origins. that's similar to Maltese... but Maltese having about 50% European vocab... but they are a tiny island under Euro rule for 800 years!
It has very simple verb conjugation. Only Scandinavian langauges are simpler in that regard, that I know.
It supposedly borrowed prounouns (!) and 'to be' conjugations (!!?) from old nordic. So it was 'thou bist', and then become 'thou art'... and until some time ago, or even today, in some small enclaves in England, people still spoke not only 'thou', but 'thou bist' (????!!!!!)
I can't remember the points exactly, but I find it also easy to see that English is a lot more similar in grammar to Scandinavian languages than the West Germanic ones.
Buuut at the same time, (I don't remember the specifics for this one either), there's a lot of core vocab that's typical West Germanic.
And like many other languages, it's supposed to have undergone revolutionary change in, what, 100 years or something? Great vowel shift, grammatical changes, etc... and then stay almost the same for 800 years.
English seems to simply fly on the face of all mainstream academia says how languages evolve.
16) Irish is supposed to have a lot of commonalities with Hebrew
17) Old Irish is supposed to have many idiosyncrasies, which I don't remember now, that some researchers say that it's clearly not even an Aryan language.
18) What the heck happened to phonetics in French? The grammar stayed pretty much the same as the neighboring romance languages, but the sounds changed quite a lot, and made so many words much shorter
19) French spelling is of course not very transparent, and if you read for example Fulcanelli's work, he hints that this is very much on purpose, for both STO and STS reasons
20) How come Castillian is quite similar in the whole Latin America? Maybe even generally more similar between countries, than Br Romance is between different states.
21) How come there are not MORE enclaves of languages like Elfdalian, Basque and Maltese?
22) How come does Faroese share only SOME linguistic innovations with Icelandic? (such as the sounds of a double "LL", which is a rare one, but not the /ski/ becoming [shi], such "ski" become "shi")
23) Why is Faroese and Danish so... unclear when spoken? I read a Danish guy saying that they themselves don't know how they can understand each other, considering how unclear some phonemes are (such as their version of "th" which sounds almost exactly like /l/), and how much they just mumble when they speak. Many ending syllable in Faroese become just mmrrhhmrhrm
I made an effort to keep all of those observations, not speculations, or unexplained possibilities based on speculation, even if the speculation is quite well-founded.
For example, IF Icelandic is not just a very conservative descendant of Old Nordic, then how come does everybody speak it up there? But that takes some speculation, so I left those out.