Helion seems to have its own savegame and screenshot path commands.. I have been using custom path commands to do this added to the preset command line section... maybe a new helion preset for that engine when added to the list might be a good idea...
Or maybe even have a way to "setup our own engine".. like how doomy dose it... where you can basically fill in a form and put in all the correct dash commands that the engine uses. This way you will not need to constantly cover every engine that ever gets released in the future yourself. In the add engine section as well as the presets you have, have one called custom that opens a setup dialogue of some kind.
Check out the "add engine" thing in doomy
https://github.com/MTrop/Doomy
Basically something like this in doomrunner would, I imagine, give you a lot less maintenance work in the future and make the app able to accommodate any engine of the future.