This Side and The Other Side are the common terms. Even if an entire episode is set on The Other Side, that term will be used for consistency.
Walternate is used on the show to indicate the alternate Walter Bishop. Secretary Bishop is equally acceptable.
For the alternate Olivia, several terms have been used. Official Fox press releases and closed captioning use Bolivia = Bad Olivia. The in-show reference is to Fauxlivia. Altivia has also seen some use among fans.
Use whatever works best, the editor will make any changes in queue to the submission. You won't get a rejection if you use the "wrong" term. However, do not alter existing usage. That will get a rejection.
Hope that clarifies things, thanks!