EDIT

the abbrev title is used for the titleCache if no lastname is available so if the cachestrategy is correct the orange colour is correct, too, or not?

It is true, that if long and abbreviated forms exist these 2 forms always are the fallback if no real atomized data exist. This is e.g. is the case for Teams too.

However, for me the semantics of orange is more indicating that these fields are REPLACED by the protected cache field and e.g other objects referring to the field will not depend on having these fields filled.

This is definitely not the case for the abbrev field which holds important and independent information and the fallback is only a solution to avoid empty caches for dirty data.

Therefore I would always keep title cache and abbrev cache independent in terms of orange.

NOTE: By the way we do have a similar issue for teams but it appears only after unprotecting and reprotecting the field which is inconsistent behavior anyway. Maybe you can fix this, too.