Before I had actually tried it, I was under the impression that the stock PCB was terrible and unusable, and so I got 2 other PCBs to use instead. For various reasons, I preferred to keep those PCBs for other builds and had a close look at the stock PCB and was ready to buy some replacement diodes and resistors or do some reflowing. Turned out it was perfectly fine. The programming was a bit of a challenge, but not any more than quite a few other boards I've built or modded for myself or friends (like getting a keymap and editor for KMAC Happy was a pain, etc.)
Anyway, before building, just do the testing with attaching the daughterboard and connecting to your computer. It might well be that new keymap and firmware needs to be uploaded to the controller first, and there's a great English-translated guide earlier in this thread on how to do it and flash the default layout. Then you can short the switch pins with tweezers and use something like AquaKey to test that all the keys work. If something is off with a few switch locations, can use a multimeter to test diodes. For completeness, you can test all diodes and resistors for consistency.
I wouldn't write off the stock PCB right away.