Just to add that yes, Welsh also counts in twenties, the word being 'ugain'.
Basque has 'hogei'.
I did a little comparative research inspired by this; I stopped when I found 'pixa' and 'kaka', Welsh 'pishw' and 'caca', which are exactly what they sound like. Both are common words in Indo-European languages, sometimes with shifted meanings, such as Hindi 'khaki', meaning dust/dirt, or Greek 'kakos', meaning bad.
But the big stumbling block was 'mendi'; a mountain. Compare Welsh 'mynydd', Latin 'mons', but root 'mont-' in oblique cases.
I doubt that either language family would need borrowed vocabulary for any of these words.
A paper published in the last few years claims to have found Indo-European roots for a number of Basque verbs, but I've not been able to track it down.
Incidentally, there are at least two words in Cornish of likely Basque origin. I am aware of a family originally from the mining community who claim (convincingly) an ancestor who was shipwrecked from one of the Armada.
'Piskie' (not 'pixie') from 'pixka' or 'piska' (depending on dialect) and 'oggi ' - pasty - from 'ogia', bread (perhaps meaning a generic baked good?).