'Blernd' violates English spelling rules only. If it were spelled 'blearned' and used as a past-tense verb, it wouldn't have attracted a second look. In fact you have already words like 'learned', 'burned', 'blend', 'bland', 'blind', ... There is nothing in that word, and no combination of noises, that isn't in English.
So, when you say that no sane language could come up with that syllable, I may doubt you or agree with you - but whether that's true about sane languages or not, English is crazy like a dancing goat, and that syllable is perfectly reasonable in it.
And, argh, don't get me started about your 'th' consonant! NOBODY (except German, again and some further-north European languages) has a consonant like that! When is it voiced and when not? No clue from the spelling. I had to practice for months before I could even say it by itself, let alone in the middle of a wreck of a word like 'twelfths' (or for that matter 'months').