Right.
All I have checked are "verify" and "align on sector boundaries" in FLAC Frontend. And the of course "fingerprints" when generating Flac fingerprints afterwards. I guess that's all needed to be checked to make proper Flac files. Right?

You are right about the FLAC Frontend's decoding speed. It's slow, but I don't mind about it too much. My FLAC Frontend version is ancient(?) 1.07.0001. Possibly I should upgrade for a newer version?

I don't know if I am stubborn, mingy or just simply stupid not willing to go for Audacity, since I already have Cool Pro 2.0. I do know that some Audacity's editing possibilities are superior(?) compared to Cool Pro like a possibility to "paint" some sonic changes right into the audio spectral view - a feature I actually dreamed of before it was finally realised in Audacity. Me myself I'm into Photoshop by my profession, that's why my "painting" idea.