Thanks.
Which subreddit did you see it on? RPGdesign and RPGcreation gave me two radically different receptions, lol. Overall I got the most helpful results from a couple discord servers.
The best advice I got was to remember you can compensate people other than just with cash, they suggested if you can't afford a professional to find another indie and/or amateur designer and offer to swap editing or writing or art or whatever your strength is in exchange for a sensitivity read (just don't be the jerk who offers "exposure")
As for finding one, I'm fortunate enough that a friend volunteered to help me out with it.
I'm actually looking to go a step further and find a Japanese co-author for future stages of development. Both 'cause I want to expand the cultural stuff and get it right, and also just because an overseas penpal sounds like a fun cultural exchange.
If you know anybody who might be interested send them my way.