I don’t think that Leia knowing this necessarily means that it’s ‘commonly known’, since she could have discovered it on her own over her lifetime.
Alternately, Rey could say “Leia would have done the same”, which leaves vague where Rey got that power but makes clear that Leia’s guidance has given Rey the mindset that she should seek self-sacrifical avenues before killing her opponents outright.
Also, we’d only have to change the mouth movements for one word rather than an entire line.