Isolate European altlang

Matthew McVeagh | my conlangs

A European alternate history language which is not based on descent from a historically known natural language.

For instance a naturalistic ATL language purported to be from an unknown family, such as one that migrated from Asia (like Hungarian) or survived Indo-European invasions (like Basque). Alternatively a language purported to be related not by descent from an ancient non-Indo-European natlang but by siblinghood/cousinhood, e.g. a Vasconic language descended from a sister of Proto-Basque, or a language descended from a sister of Etruscan.

One thing that occurs, if it's meant to be realistic and situated geographically and historically in a familiar Europe (even if an ATL one), it would need to have some qualities in common with known OTL natlangs or established ATL conlangs... examples being borrowings from other languages, such as Latin, German or English. There would be a word for 'television', and it would probably be quite like 'television', unless I insisted on a purist solution like German 'Fernsehen'. I imagine this is an issue already faced by those who've created altlangs, but they are mostly based on extrapolating from well-known OTL natlangs. This would not be, I'd have to make the non-IE base up, make it diachronic and full of irregularities and evidence of change, then add borrowings from all different historical periods from natlangs or even made-up IE altlangs.