Okay, some updates:
1. Hubz, thanks for the assistance, but unfortunately it may have to wait as I don't have enough funds to contribute right now and the only game I've found from either company is below.
2. There is a copy of the undumped PC-6601 Bosconian here:
https://www.ebay.com/itm/Bosconian-for- ... 0005.m1851However, as you can see, it is extremely expensive. We'd have to raise an insane amount of funds. Thankfully, there is someone who's offered to dump the game: the previously mentioned native Japanese speaker. He messaged me and said he's very interested in helping to dump it, but the seller won't ship to Japan. If anyone can help with this, you can mention him once he's approved on here. (Moderators: his account name is Kyabetsu.)
3. @famicomical I've messaged you on FW regarding the SF.