You are being too picky. Mondince is probably one of the better sellers to work with on the lower end of the price spectrum, but they're still 1/3 - 1/4 the price of the higher end Chinese frame companies such as XMCS, Lightcarbon, Winspace, Quickpro, etc. They do a good job in my experience - when I had an issue with the saddle clamp for the offset seat post that my FM336 came with I reached out to Jack for replacement hardware since the issue was one of the cross/barrel nuts. Jack ended up sending me replacement hardware as well as an entire zero offset seat post for free that got to me within a week. Are the brake mounting posts perfectly flat and pristine on my frame and fork? No, but they were masked well during painting and flat enough to have minimal rub. I ordered a facing tool to improve them, but it's such a minor problem I haven't felt the urge to face them just yet.
The rivets are a miss, yes. I would've been interested in hearing how they address that but it sounds like you'd be better served by one of the bigger players. I think for those looking for quality frames in the $500-800 range that may require a small amount of finishing work Mondince is a better option than SPCycle, Meinier, Seraph, etc. Light Cycling seems promising, but no one has built one up yet so the verdict is still out for them.