When Boshin War came, thee regions (toyama, nagoya, hokaido) change ownership to REB by event. It may not look that bad, but on recapture they convert to permanent colonial provinces (maybe REB unciv nation). Your country will be effectively split in half (by toyama, nagoya) and second half disconnected from capital by "colonies" loose national territory status (became only claimed), you loose 1/3 of consumer market.
Advise: Remove from event "change ownership" lines BEFORE Boshin War.