Fil-C is an innovative approach and a great technical achievement. However, I wouldn't suggest that it is an universal solution without caveats. For instance, the performance penalty of up to 4x is not acceptable in a lot of cases.

Also, the c2rust output is rough but not hopeless: There are real world success stories of rust projects that were bootstrapped via c2rust, e.g. https://tweedegolf.nl/en/blog/151/translating-bzip2-with-c2r...