The problem why eventing in Construct is slow is because you're required to scroll down to get to several actions.
I think a simpler solution is to replace the list with a tree. All items are collapsed by default, and a single click on an item will expand it. This will pretty much eliminate the need for scrolling, and will make eventing much quicker.
I don't know about anyone else, but I've done so much event coding in Construct now that I pretty much have the list memorized. When I code events my scroll-wheel finger is on auto-pilot and stops where it needs to. Having a tree that you need to click on would just slow the process down by adding extra clicks.
Unless Construct could memorize what nodes I have expanded so I don't have to click them every time. That would be okay.
The one major thing I think would speed up event coding is sorting objects into folders, and having the option to exclude objects or folders of objects from the event lists (for instance, background tiles that don't have any purpose except decoration). But that's on the to-do list I think, so I'll just wait patiently.