The toroidal transformers are all common-mode inductors. The two-winding one (page 3) I'm not sure about, it's much too fine wire to be handling much power (and doesn't seem to be wired to much of a load?); the rest are three windings, so, I take it this unit is made for 3-phase conversion?
Wait, four pins on the far side, I think that may be a potential transformer (i.e., used to sense the voltage on the primary side, by a calibrated ratio), that could explain the high turns ratio. Still, no idea why the sectoral wind.
Also the nearby (quick connect) terminals are labeled PVn(+/-), which sounds like DC (photovoltaic panel connections?). Can't tell how they're connected to the transformer-thing. So, dunno.
Anyways, the smaller E-core transformers are probably for power to various subsystems, up to a hundred watts or so (bottom p5, yellow rectangular thingies).
If there's any mains isolation in this thing, it's probably the potted mess on page 4. The boards are all about managing, handling, monitoring, switching, etc. the PV and mains supplies, and the actual power conversion connecting between them, I'm guessing, was wired here.
Without labels on the lugs, and seeing where they were bolted to, I can only guess this is the case. The box does seem long enough for three transformers, which would be needed for the three phases. There should be some filter inductors somewhere, or maybe they're internal somehow (e.g. resonant converter).
Can't tell what top of page 5 is; backside of the transformers box? Looks embedded in a heatsink, or maybe that's just a cutout. Clearly bolts to the main power switching board (bottom p6 / top p7).
That WiFi module is all kinds of jank, looks hand made. Completely unwashed, gooped up with rosin.
As for ratings, what does the manual say? What standards does it conform to? You can learn 100% of what you need to find in there.
If it doesn't say it meets some standard, assume it doesn't! Think like a lawyer -- this is a legal question more than electrical. If it doesn't specify isolation, like, it shouldn't even be sold probably, and definitely won't meet your system requirements! Now, you will have to check standards and what they mean, for that to make any sense, but such is the responsibility of the system designer.
Tim