Event Editing, Help A Noob Plz~

Which scene are we talking about here, the first event there on the cliff with Magitek Armors? I'm not sure what all you'd like to do there, but if it's just having the Terra character have more presence, then yeah swapping her with Vicks or Wedge there just for that scene would work well, there's not all that much more I'd imagine could be done there because of how small the cliff map is and how much space the Mtek Armors are.
You can just switch them back after the map fades out before the trek through Narshe if you don't want them swapped past the cliff. Would just require jumping to some free space, but that's another thing.

Maybe experiment swapping them and see if it works out in any way, if not then some more thorough eventing will most likely be needed!