Multiselection is a "nice to have" imo, but not crucial.
Well, if single selection is all you need, then cut-paste already supports that.
What about a scroll area on the left side of the event sheet view that scrolls JUST like it does when using touch, but then the rest of the event sheet view is treated as a mouse with click/select/drag?
I don't think this is a sensible UI pattern. I don't recall ever seeing any other app doing something like that. I've only ever seen other examples that were based on switching modes, so you only do one thing at a time, not both with magic invisible areas.
I like to think this would be relatively straightforward to implement as the "touch scroll" code already exists in c3, as well as how mouse behaves within the event sheet view.
UI is extremely complicated and hard work to implement. If it looks and feels easy, it's because a huge amount of work has gone in to getting it to that point.