No, they sadly have not found one. Aberystwyth university plans to write one.
https://www.theguardian.com/science/2025/dec/08/linguists-start-compiling-first-ever-complete-dictionary-of-ancient-celtic
P vs Q will be fun...
A complete dictionary of the Ancient Celtic of the British Isles, apparently.
So mind your ps and qs eh? ;)