I adored PC gaming when i was little and i still do, but nothing gives me that thrill like a good old pc running dos, and your program allows me to do so without assembling a vintage computer myself. (I have no room for it

Ok i have a weird question. I am a bit of a midi nut and i use a few midi devices to get that authentic sound again :
1.) Roland Sound Canvas 55 MK II
2.) Roland MT-32 (first generation)
3.) Roland Sound Canvas 8850
I was thrilled to notice that any midi playback was directly sent to the roland UM-ONE isb/midi interface. So games using normal General Midi sounded perfectly (sometimes with the use of SOFTMPU).
However, games using an MT-32 all sound wrong, i never receive any sysex message to the device so specific sounds aren't getting programmed and even normal instruments sound completely wrong.
For example, the classic sierra games and others used to send message to the display while programming the device and i cannot see those as well.
So it makes me think anything sysex related does'nt get passed to the device.
Is this normal behaviour at the moment or is it a bug ?
I tried with and without SOFTMPU and with /DELAYSYSEX but nothing seems to work.
Any way to get it to work ?
I use a compiled dynarec build (PCem_v9_rev216) but even the normal latest build exhibits the same problem.
Also, i use an intel I7 920 processor clocked at 3.4Ghz and i struggle to emulate a 486DX4 75 Hz computer, i suppose i'm just not giving it enough juice or should i be able to handle higher speeds ?
many thanks !