I think I was able to implement them.

Except for 91 = Reverb Level, because there is no m_pSynthesizer->SetReverbLevel like for the other parameters. Probably we have to implement it in minidexed.cpp. Since this is a global (non-TG) parameter I was not sure how to do this. Maybe @rsta2 can point me in the right direction?

Regarding 91 (Reverb Level) I'm honestly not sure. Perhaps it's better to use TGParameterReverbSend instead, because it is local to the TG, and let Reverb Level only be modified from the UI. You can change TGParameterReverbSend from mididevice.cpp like that:

m_pSynthesizer->SetTGParameter (CMiniDexed::TGParameterReverbSend, nValue,  nTG);

Some parameters are not in the MIDI range 0..127. They must be mapped to that range.

Perhaps it's better to use TGParameterReverbSend instead, because it is local to the TG

Yes, it'd be more consistent with the other params indeed.

Some parameters are not in the MIDI range 0..127. They must be mapped to that range.

should take care of that, right?

constrain() only checks, if the parameter is in the given range, but does not map it. To map from one range (MIDI) to another use:

nReverbSend = (unsigned) maplong ((long) nReverbSend, 0, 127, 0, 99);

10 = Pan: 0-127
71 = Resonance: 0-99
74 = Frequency Cutoff: 0-99
91 = Reverb Send: 0-99
94 = Detune Level: -99-99