as for filter envelope generation part - it looks the same as AEG in the term of change rate (as noted in html docs).
so time for full 0-0x1FFF change is aproximate 8x longer than AEG times tables, not ~4x like DCDBSysArc990907E.doc says.

but correct EG rate formula is still unknown, for both AEG and FEG (if KRS!=0x0F).
docs says its (KRS[0:15] + OCT[-8:+7]) * 2 + (FNS>>9) + RATE*2
some SCSP/AICA emulators calculate it this way, other like AO uses
KRS[0:15]*2 + OCT[-8:+7] + (FNS>>9[0:1]) + RATE[0:31]*2, so octave isnt *2
others calculate (KRS+OCT)*2 but add it only if value >0 (I currently use this)
but sadly its really unknown for now how exactly EG rate value calculated, in both SCSP and AICA.