I am using JS Animated Contact Form with this line of validation regex:
rx:{\".name\":{rx:/^[a-zA-Z\'][a-zA-Z-\' ]+[a-zA-Z\']?$/,target:\'input\'}, other fie
I used
A-Za-z-ÁÀȦÂÄǞǍĂĀÃÅǺǼǢĆĊĈČĎḌḐḒÉÈĖÊËĚĔĒẼE̊ẸǴĠĜǦĞG̃ĢĤḤáàȧâäǟǎăāãåǻǽǣćċĉčďḍḑḓéèėêëěĕēẽe̊ẹǵġĝǧğg̃ģĥḥÍÌİÎÏǏĬĪĨỊĴĶǨĹĻĽĿḼM̂M̄ʼNŃN̂ṄN̈ŇN̄ÑŅṊÓÒȮȰÔÖȪǑŎŌÕȬŐỌǾƠíìiîïǐĭīĩịĵķǩĺļľŀḽm̂m̄ʼnńn̂ṅn̈ňn̄ñņṋóòôȯȱöȫǒŏōõȭőọǿơP̄ŔŘŖŚŜṠŠȘṢŤȚṬṰÚÙÛÜǓŬŪŨŰŮỤẂẀŴẄÝỲŶŸȲỸŹŻŽẒǮp̄ŕřŗśŝṡšşṣťțṭṱúùûüǔŭūũűůụẃẁŵẅýỳŷÿȳỹźżžẓǯßœŒçÇ
which supports almost all the chars in Europe. Source of truth