Off of my limited experience on RDM so far:

I find that the need absolute need to do a Corps-a-Corps/Displacement combo a bit stifling given that there's plenty of times I'm not going to want to dash in or out and introducing Engagement later on just to solve that problem seems needless. If all three were on the same charge system (3 charges so that you can keep 2 in reserve,) with the same potency (so you aren't inching forward inbetween dualcasts to spam displacement) it'd be much more flexible.
Engagement can just become an untargeted dash that deals aoe damage so that it has another purpose given that the above change would just let you corps-a-corps multiple times instead.



I also find Acceleration to be pretty boring. Oh boy, 50% extra chance for a guaranteed Ver-stone/fire. I think it'd be more fun to make it a RDM equivalent of BLM's Triplecast, meaning that it's Swiftcast with an extra kick. Maybe just Swiftcast + a followup Dualcast so instead of just guaranteeing a Ver-stone/fire proc, you instead have a chance to fish for more procs while you start spamming Veraero/Verthunder. This spell is called Acceleration after all, if it was going to just guarantee a proc, it should have been called Focus or something. It should also get a trait for 2 charges for extra versatility and to emphasize the difference between RDM and BLM. RDM has 2 instant casts that they can stagger while BLM has 3 that they all spend at the same time.