Edit: I test with midi out and the microsoft general midi player. Bass sound correct.maybe general midi have some controllers to transpose ?. I see in general midi controller map RPN. RPN
GM defines several Registered Parameters, which act like Controllers but are addressed in a different way. In MIDI, every Registered Parameter is assigned a Registered Parameter Number or RPN.
maybe some songs change this, but VSTi can not recognize it ?. I show screenshot of bass track. maybe somebody understand what is done. if transpose with rpn can change, then its maybe usefull that RC have a option. add transpose RPN to convertet midi. this mean that the the rpn is not insert and the notes are transpose from RCin wiki Registered Parameters are usually called RPNs for short.
Setting Registered Parameters requires sending (numbers are decimal):
two Control Change messages using Control Numbers 101 and 100 to select the parameter, followed by
any number of Data Entry messages of one or two bytes (MSB = Controller #6, LSB = Controller #38), and finally
an "End of RPN" message
The following global Registered Parameter Numbers (RPNs) are standardised  (the parameter is specified by RPN LSB/MSB pair and the value is set by Data Entry LSB/MSB pair):
0,0 Pitch bend range
1,0 Channel Fine tuning
2,0 Channel Coarse tuning
For example: RPN control sequence to set coarse tuning to A440 (parm 2, value 64):
101:0, 100:2, 6:64, 101:127, 100:127
But a complete sequence to send i do not see in wiki . only this
1 Fine tuning
2 Coarse tuning