No worries. I was pulling my hair out a year ago trying to fix the heat creep problem with PLA, so I can certainly understand the frustration. I will try to check consistently.
I think even if the rear shroud is cracked or compromised, it should still be much better than stock.
Something else just occurred to me also. Before I came up with the heatsink shroud design, I did a modification to the actual extruder body, putting the same 5 volt micro fan on it, and directing air through channels adjacent to the filament and out of the bottom (details here: PLA Heat Creep - SOLVED )
That approach was only partially successful, but when I installed the current fix, i did not remove the fan from the rear extruder body
So, my rear extruder also has a fan running in the body of it (I never installed it on the front one). Is the current shroud and fan fix working for PLA on your front extruder, but not the rear? I wonder if I am still getting some benefit from that extruder body fan. I have done 99% of my printing on that extruder. The few jobs that I did use PLA in the front extruder (without the body fan) did work, though.