The discussions you probably are referring to are related to the step sequencer implementation, and I’m pretty sure it was implemented there and there was some discussion about lv2 implementation. I believe the step sequencer implemented an external MIDI clock (@riban will know) but most of the testing was done running on it’s internal source ( because step configuration was a concern for a while).
Most ‘interesting’ devices in the zynth world are best viewed as lv2 devices, and you can get midi in and out of these via the channel you allocate to that effect albiet with the occasional use of patchage to patch the jack layers.
As to what’s available in the MIDI fx world of LV2 I’m not the person to ask but I suspect there are all you describe and many more, so if you could hunt syh beasts down and comment that would be to the benefit of all and would obviously relieve you of any cumbersome duties.
What would you expect the devices you describe to do, because I suspect the step sequencer in the zynth might well give you a fair insight into the zynth thinking on MIDI devices.