Sorry you had to cancel the booking.. I would be disappointed too.
I'm from Singapore, and our working language is English. It will be unfortunate if cruises out of Singapore indeed targets Mainland Chinese pax instead of Singaporeans and its neighbours. We wouldn't want to board a cruise only to eat Chinese food (that we can get plenty of in Singapore) or be immediately transported to China fighting for survival onboard.
The lack of Solarium access will be a deal breaker for me. I'll try to get some clarity from RCCL's Singapore office before booking my cruise this week, fingers crossed!
By the way, a Japanese cruise sounds amazing. Imagine a polite, socially-aware, and orderly crowd!