Hopefully you'll get what you are trying to accomplish for, but expectations should be set. There are several hours of "learning curve" here, and then each "game" will comprise of 3 streams) will probably take 1-3 hours of editing (likely longer), then an hour or so of export (based on a 48 minute game). And if you're uploading to YouTube or the like, another hour. Yes, some of this time you won't need to be doing anything (like when the video is exporting, or uploading) but each of those tasks has a learning curve. Video is just big and heavyweight. If it's something you (or one of the parents or other interested parties) has an interest in, then it's a great way to learn.
Note that in more advanced editors like FCPX or Resolve, you can burn in the timecode and reset it (such as when the second half starts). Way more efficient/faster than bringing in a third track of a video just showing he clock. And, you can use the method Apple recommends:
iMovie for Mac: Create a split-screen effect - Apple Supporthttps://support.apple.com/kb/PH22930?
Sync the camera clips to tip-off, which presumably each camera can see.
I understand the importance of the game clock with respect to the game (Go Warriors!). But adding a 3rd camera feed to this makes things pretty complicated for iMovie, and even FCPX and Resolve. If you can live without "official time" I think you could be close within a second. If there's a way to use (the time code instead of the official clock video, that would really speed things up.
If you figure out a way to automate this, contact me - we'll be millionaires together!