Plastic housing for the coil pack is cracked

It can depending on why it cracked. If it is simply due to the aged plastic getting brittle and cracking versus the coils getting hot and swelling and that cracking the plastic. If it still runs good with no misfires or other issues I would probably just take some silicone and fill in the cracks to keep moisture out. If however there are signs like misfires when it rains or a code for a coil issue, then I would replace it as it could be from internal damage and that could result in PCM issues from the coils pulling excess current.

Okay, that code is for cylinder 4 and says that the spark in the cylinder isn't lasting long enough. Common cause for that is a bad coil or the PCM coil driver is failing. A quick way to test the coil is to simply swap it with the coil on number 1 and see if you now get a code for cylinder 1. However if it is cracked I would replace it as it's likely from heat due to an internal short.
Swapping it would show if that was the case or if it's a different issue, say you swap it with 1 and the code stays on cylinder 4 and nothing changed, that would show it's the PCM or the wiring to it. Those coils all get power from the same source on the Brown wire with gray stripe. A quick test using a test light on each coils power feed would show if that was okay. Then use the test light in the place of the coil and see if the light flashes at all. If you have power but don't see it flash then it could be the driver transistor at fault.

PCM. You could use a chunk of 2 conductor wire gently inserted into the connector for the coils and extend it so you can see it from the seat area. The code you have is indicative of a bad secondary in that coil. It would also explain the misfire in that cylinder. At the moment I doubt even a dealer would be able to help you as many PCMs are on backorder. You could get a used one though if yours did test bad.

Yes, a used one would need to be programmed as well, but at least you might be able to find one if it's needed. I would test the coils and be sure where the problem is first though. All of the coils share a power feed so if you are seeing battery power at them then that is good although 11.8 is low for a good battery.

Yeah, they are expensive and it's getting worse on newer vehicles. The TIPM at least can be rebuilt reasonably low cost and rebuilt ones are easy to find. The PCMs on the other hand are very suspect as rebuilt units. I've seen "rebuilt" ones off the auction site that rhymes with flea ray that failed in 20 minutes from install!