I don't believe the team behind the retranslation patch ever did any work on Flight Diary or Snow Presents. I think those were separate fan teams that fizzled out very quickly.
It would be great if Moenovel put out an official 18+ patch, but I think it's extremely unlikely, especially since the entire Ageha/Hotaru side story appears to be cut from the English release.
EDIT: Also, I don't know if the retranslation team would work on Flight Diary. On Reddit MeruP said he might do work on a restoration patch, but the original translator is busy with other projects. IIRC he's also not interested in translating vanilla H stuff, but don't quote me on that.