Please read my post again. No application will edit FLAC or other lossless files directly. They must be decompressed, edited and recompressed. Whether the program does so automatically or requires the user to provide a decompressed version makes absolutely no difference to sound quality. Lossless is lossless.
I do not think Audacity will either.
Do NOT use mp3 as any kind of intermediate step. Use only lossles, such as wav, until the very last step, which is to encode to mp3 if that is what you you need. If the target is an audio CD, as opposed to an mp3 CD, then burn that directly from the lossless file, not from mp3.
As long as "edited the file" only means joining together multiple wav files into a single file, with no other processing, then there is no loss in quality.