Clicking [Finish] at the end is redundant
My only issue with Selene - since I use it for very simple batch conversions of FLACs to M4A and nothing else so far - is the [Finish] step at the end. It doesn't seem necessary, there's no other thing to do at that point anyway, so we could simply return directly to the normal screen when the conversion is done, and maybe add a "Completed" marker next to each file so that a user who went away from the computer and comes back isn't left wondering whether anything even happened at all.
Actually it's not redundant at all, but you wouldn't be able to guess this.
When the conversion is completed, you can still drag and drop new files on to the window, and they will be converted using the settings you already have selected. Pretty handy, in fact.
The challenge is that this isn't mentioned anywhere, so I only found out by trying it out one day on a whim.