Right now Microsoft flow automatically generates names for the dynamic values you want to use from your powerapp.I think it would be beneficial to provide us with the ability te rename / refactor existing parameters for readability etc..I doubt this would be a hard-to-enable update!
Have also posted this in Flow ideas: https://powerusers.microsoft.com/t5/Flow-Ideas/PowerApps-integration-Remove-Rename-parameters/idi-p/...
Please vote for this there also, thanks!
With this should also come an enhancement that allows you to see the newly added or removed Flow Variables in the PowerApps parameters list. I have found myself having to export the existing Flow, and then Import it under a new name, finally reassociatating it with the PowerApp to finally see the added/removed parameters.
This is a must for code maintainability. I have dead parameters on multiple flows, and so have to pass in garbage values from Power App .Run() methods in order to make it work. Hard to believe this isn't a top priority to fix.