Download the manual and look what it says.

I Looked at the manual already... doesn't say anything about MT-32, CM32, CM64.
Also took a gander at the SC-88 and the SC-55 manuals these are the listed maps in addition to the native maps:

SC-88st - SC-55

SC-88Pro - SC-88 and SC-55/SC55mkII

SC-88 - SC-55/SC-55mkii

SC-55/SC-55mkii - MT-32

You could always make a custom MT-32 map yourself and send it to the SC-88st via sysex.

See here for some guidance:
Re: Remapping sounds on Roland Sound Canvas?

Mu0n wrote on 2020-07-25, 14:19:

I'm wondering if my inbound (from Japan) SC-88ST unit can somehow play back those CM series specific sound effects in games such as Out of this World or Elite Plus?

no.

If the SFX are played from the drum channel, possibly, you could use the CM drum map in that case. The question would then become - does the music play correctly?

Spikey wrote on 2020-07-31, 14:44:

If the SFX are played from the drum channel, possibly, you could use the CM drum map in that case. The question would then become - does the music play correctly?

Unlikely, because the synthesis methods are different.

yawetaG wrote on 2020-07-31, 15:12:

Spikey wrote on 2020-07-31, 14:44:

If the SFX are played from the drum channel, possibly, you could use the CM drum map in that case. The question would then become - does the music play correctly?

Unlikely, because the synthesis methods are different.

Yes, I'm fully aware of that. 😉