i had a non-french canadian company (i'm ameri-can) try to get my domain name twenty years ago.
they wanted to buy at some point, i asked for something they shit on -- maybe $10k? -- they said no, sued me thru icann, i won -- fuck them -- and twenty years later i let the domain expire, and they got it and now use it.
they could have paid what i wanted, or worked some kind of deal with me -- i'm often a reasonable person -- but once they got testy, it became unlikely that i was going to make a deal, and once they went to icann, it was never going to happen unless i got rich from selling it, or stop caring about it.
my first response to the french would be like, 'go fuck yourselves. i love french people and french culture and french fries and for saving us from the brits, but you particular guys are a bunch of assholes -- and your app sucks -- vive la france!'.
i'd prob try to ping an IP lawyer, then just hold onto it forever, or until they met my price, which would be some very significant sum, based on the company's revenues/worth.
i don't know domain/ip law, but "don't buy and use a domain that is used by some asshole french company" doesn't sound like law to me -- unless maybe it's a '.fr' --- then maybe.
i'd make them pay for fucking with me. 100%.
this is still gd America (if that's where you are), and we got some serious mf property rights (too many, imo). time to use/abuse them mf laws just like those french assholes abused the rules of decency. :-D