I would like to report 2 bugs that affect both bank/program select dialog and ReaControlMIDI VST so I think it's a general parser error.
1. The parser completely ignores the BankSelMethod directive in the Instrument Definitions sections. More precisely it always assumes BankSelMethod=0 so treats Bank numbers as MSB+LSB addresses.
However there are 4 possible (0-3) BankSelMethod values and each represents a different bank addressing scheme. I have not met all of them but
BankSelMethod=1 (GS style MSB only addressing) occurs frequently.
0 Normal - bank select MSB and LSB matter
1 Only the MSB is used and defined
2 Only the LSB is used and defined
3 Only program changes are used and defined
2. Ins files resembles windows ini files and in ini files the official comment sign is ';' and not '#'. So in ins files e.g. [Roland GS Var #1] is a completely valid section name. In spite of this Reaper's parser ignores everyting after the '#' sign.
Although AFAIK no official documnetation is available you can test in Cakewalk products.
I have attached a test ins file that can reproduce both bugs in Reaper.