Current at Pmax appears to be 10-11A, so it's the same deal. If you put strings in parallel with 20-22A of input current, the unit will ignore anything over 15A, so you'll be limited to about 75% of the max rated output of the array.
148V may be too much in cold conditions. Power stations tend to be a little more forgiving when you exceed Voc, but I wouldn't count on it.
The power claims and the MPPT limitations of "solar generators" are often misleading and confusing. In order to get 1600W, you need:
1600W / 15A = 107Vmp, not Voc. Voc would run about 133V, which is a potentially a concern with exceeding 150V.
With the above restrictions, you need to carefully select your panels. IMHO, the manufacturer's do this to encourage you to buy their panels that can be selected to get very close to the 1600W output.
4S2P fo the Rich will only get you:
81.6Vmp * 15A = 1224W, BUT it will produce that 1224W for as long as the 1600W array can produce 1224W.
Unfortunately, the higher voltage of the Hyundai means a 2S2P array will only get you:
77.8V * 15A = 1167W
Rich solar: 20.4Vmp, 9.8A Imp
Hyundai: 37.9Vmp, 10.7A Imp
It wasn't entirely clear to me initially how you connected things. Now I think I understand better.
Any strings you put in parallel MUST be as closely matched as possible for Vmp (up to 10% variation). If you have too large a disparity, the higher voltage string could potentially discharge into the lower voltage string, OR the MPPT may figure out it can pull the voltage down even lower and get some power. I'm pretty sure that's what was happening.
38Vmp * 15A = 570W, which was your prior peak.
4S 200W in parallel with 2P 400W is a non-starter.
4S 200W in parallel with 2S 400W meets the 10% variation in Vmp. However, you're trying to move 20A+ when it will only accept 15A, so you get hit with at 25% penalty per array.
You'll get about:
38V * 2 * 15A = 1140W