If you can find a southpaw WindX, that might meet your requirements. Unfortunately only the right hand version seems to be in stock, so you would have to check aftermarket.

I just took a Sol 3 to New York for a week. Traveled in its case in my carryon.

Caps Lock is a dead key in such an important position. I personally remap it to Backspace on tap and layer on hold (though many people do Control for HHKB).

I have arrow keys under my left hand on that layer, so if I need to quickly move in an editor, instead of moving my right hand to arrow keys, it’s just hold a key and tap.

Vala is legit, I’ve bought several times from them.

It’s possible that you fried some diodes on that side of the board matrix, but it could also be that there’s still some moisture in there. Compressed air to the back of the PCB can make sure it’s dry.

It’s possible to get to the back of the board and replace the diodes if you are comfortable soldering. You can see the back of a K70 here: https://youtu.be/ZeIqMQ2WDaY?t=340

I’d maybe consider this an opportunity to get a more disassembly-friendly mech, though…

I have a Sol 3, which is very premium (so may not fit your needs while you’re exploring) but it does meet all your requirements and is better-built than the Moonlander (metal top and bottom, screwless).