This entire thread is about using a European model inverter (single phase 220V 50 Hz) set for 240V 60 Hz, and wiring for use in US 120/240V split-phase operation. In this case, factory removed a screw to let what had been "Neutral" float ungrounded, so the 240V output could be centered around a new grounded neutral.
We're not sure the physical configuration of "Neutral" on the PCB vs. grounded case. It ought to have "Creepage and Clearance" in compliance with UL requirements. If I'm reading table 2K correctly, that needs to have 2.6mm airgap.
The reason for testing the PCB while touching it is to see if the gap is only produced by the PCB not being firmly clamped to case. If a gentle push causes PCB to make contact, that indicates it was maybe 0.1mm away or at least well under 1.0mm. The test is performed with low voltage (and ohm meter), but line voltage or typical transients could arc across.
A 12" wide PCB held by screws on the edge, when it expands and contracts at different rate from aluminum casing, will bow, possibly making contact. For "Neutral" and ground to be reliably isolated, they need significant distance between them in X, Y, or Z direction. Because a screw was used to join them, it appears they are less than 2.6mm apart.
These units are guilty until proven innocent. Fearmongering is raising valid concerns, which can be set aside when examination or test shows they are unwarranted. The "blown up" units were ones where this screw was still present. If the PCB can make contact in one with screw removed that is the likely outcome. It is possibly removal of the screw provides decent isolation (perhaps not as large a gap as UL requires), in which case it could function satisfactorily. But due to how PCB holes and vias are usually designed, I don't think that would be the case unless designer planned for being able to isolate it.
Schematic, ground bar, and panels - difference is, although we were required to sink a ground bar, we were also required to connect a ground wire from panels back to SCC/inverter. And wire from there back to ground rod of utility entrance.