one letter away from fetal???????

Not sure I can support the idea of "one letter away from . . . . "

Yes, the fetal group idea isn't really in keeping, plus it's not, in itself, a real word outside of the US, most of the rest of the English-speaking world still retaining it's correct spelling of foetal.
But TBH I think the grouping of a random group of French words was even worse than that. Obvious, in the context of the rest of the grid, but there's no link between them apart from being French.

I agree with the other comments. "One letter away from" is a poor link, especially as three words require you to change a letter and one requires you to add a letter.

I concur. Fetal? French verbs?

Liked the Trouble group though.