Dear Francky5591,
As a native Latvian speaker, I must tell you some lingustic reasons, why word "baskiski" is hardly acceptable.
It is only since XIX century that Latvians had formed adverbs relating to ethnonyms. The sufix '-isk-' that is related to Russian '-Ñк-' and German '-isch-', was not used for forming adjectives before. Where foreign language texts suggested usage of adverb relating to nationalities, Latvians used expression "... valodÄ" ("in ... language"
or more archaic form "... mēlē" ("in ... tongue"
. It is only through influence of Russian and German languages that promoters of contemporary Latvian suggested usage of adverbs related to ethnonyms like another languages do.
However, not all ethnonyms are not suitable for making adjectives in Latvian. Some exotic ethnonyms are not subject for forming corresponding adverbs. For example, "Thai" (as adverb) should be translated "tajieÅ¡u valodÄ", as "tajiski" sounds bad and needs additional explanation. Moreover, if a word contain consonants "sk" in final syllable, they might be softened for making derivations. For example, from word "Bauska" (a city near border with Lithuania) Latvians had formed word "bauÅ¡Ä·enieks" (inhabbitant of Bauska). However, as consonants "sk" in word "baskiski" are met two times in following syllables, it sounds awful and suggest additional information what does the speaker of this word meant originally. The Institute of Latvian Language does not accept alternative noun "baskietis" and adverb "baskietiski" that sound better from the perspective of native Latvian speaker.
Latvians with good sense of languages would avoid word "baskiski". It is not of linguistic purism but from a perspective of better understanding of original idea that I asked to make a change. As not all lingustic things are met in every language, you should understand that my suggestion doesn't influence retaining corresponding renderings in languages which by rules of grammar allow a usage of adjective instead of construction of main word and explanatory subject.
I hope you had got a better understanding of the subject.
Best regards,
durklis