First, GHex is Here
Second, you set the tempo errrr BPM in db.
The midi you read to help ya with the note placement does have a function to display BPM (look in puppetz' first post for directions on how to find/use it!) which can vary song by song and section by section.
Even then, it's usually wrong anyway.
Use the BPM shown in FL as a "jumping off point" of sorts.
If a song goes out of sync even with the BPM in FL set in db, use anchors to fix it.
Third, don't waste your time with .chart -> .sng -> NOTES.
It destroys variable BPM.
I know because I tried it! :p
OOPS! I made a typing error.