I think this is not because of a lack of programming, it’s more like technical not possible. I also would like to see that a VST can be controlled by pattern effect commands, but that’s technical impossible. At least that’s what a friend of mine, one of THE computer experts of the world (he said he also knows taktik), told me, and I believe it because it makes sense. Very sad, but that’s the way it is. Personally I’m searching for a way to slide from a note to another specific note, for example from c-3 to g#3 (I want to do some funky stuff again), which isn’t a problem if the tone is a sample, but if it’s an instrument from a VST it’s not working. Basically it’s the same problem like yours above. You can’t control a VST with some Renoise commands (except the instrument automation), you have to do it directly within the VST. And every VST is a little bit different to handle. So I should have to find another way. Just like you did right now. 
By the way, there’s another shortcut for your duplication of your desired track. Press Ctrl + Alt + D to duplicate your desired track including EVERYTHING. If you do this, then not only your FX VST chain is being copied, also everything you’ve set in the pattern editor. That means you can create an exact clone of your whole track by pressing three buttons at the same time. It can’t be easier than this. 
