CUS North Approach Track Numbers

My frequent downtown walks takes me along the alley between Randolph and Lake above the CUS north approach tracks. I know we have some people here working for Amtrak or Metra who can answer so how are the tracks designated in that stretch. Looking at the numbers on the switch machines, it looks like those numbers encode the track numbers in them (e.g. crossover 452 goes from track 5 on the west end to track 2 on the east end and I'm guessing the leading 4 indicates its CP LAKE since a block north at CP CANAL, they all start with 5).

If I've cracked the code, then from geographic west to east, they are:
Track 4 (under the alley, AKA Butler Brothers track)
Track 3
Track 5
Track 2
Track 1
Then there is the track that, from north of Lake St., splits off of 1, swings out towards river going east of a Lake St. bridge support, then has switches with what I believe are the north ends of station run-through tracks 23 (embedded in roadway) and 21, and then comes back and rejoins 1. I have no idea what this track is designated.

So, 1) can someone who knows confirm the 4-3-5-2-1 ordering and 2) say how that track that balloons out by the river is designated.

Very observant, sir! You are correct on the order of the Main Tracks. (It is so because Main Track 5 "begins" at the switch off of Main Track 3 at CP Lake).

The "ballooning" track you refer to is called the "21 Connection Track", as it provides the access to Track 21 (and Track 23 as well). Incidentally, Tracks 21 and 23 proper both end at CP Washington, and from there they are referred to "21 Extension" and "23 Extension", northward, until they terminate on 21 Connection.