I'd like to know more about Park Jr. as well, he designed the course where I play, you're right, there does not seem to be much writing on his architecture. Possibly his style is considered too bland in this age of dramatic visuals.
Speaking of my course, it could be due to very economical and low-profile style of his, which may or may not have a lot to do with the limitations of the times when it came to moving earth and shaping the ground.
His strength at my course would be his clever routing and placing of greens, making use of all the natural land formations, introducing few that required much earth-moving. The bunkers are not penal, and placed sparely but thoughtfully.
Most creative license seems to have been taken in designing the greens, there are many steeply canted flat ones (always back to front) or two-tiered ones with nasty putts. A constant rule seems to be never be above the hole, and don't even think about air-mailing the green, the pitch back will be impossible to get close. Always open-fronted greens (except for fiercely defended par-3s) where the smart play is often to under-club, going right at the pin ends up being a sucker's play often.