Also it would appear that cubase itself may not be using note expressions under the covers to handle multiple expression map articulations on the same timestamp. So even cubase is missing this problem, much less all other hosts.
In order to make everyone happy, all hosts need to detect cc-note-cc-note sequences on the same timestamp and convert that to the right series of note expressions and notes before calling back to the vst3 plugin. Trying to use parameters for that will lose the sequence. So all hosts including cubase would need to detect that and handle it with internal note expressions instead of parameters.
Likewise all vst3 plugins everywhere need to be looking for note expressions which not all are. But they should be anyway before shipping a vst3 plugin.
As noted earlier, cubase expression maps are unable to resolve this problem either. Poly articulation chords are impossible with cc keyswitches in the instrument.