OneStream EmployeeThere aren't many apis to look at stage data; there is FdxExecuteStageTargetTimePivot but it feels a bit overkill here. Most people will just go and query tables: open connection, sql etc. Doing it in transformation rules will likely be pretty slow though, even with caching hacks through globals. Besides, looking at stage data might mean you miss out on potentially important information loaded with forms, journals, or other workflows.
I'll be that guy: I don't think this sort of operation belongs to Derivative Rules at all. You're doing financial calculations that are better (and more easily) done in the cube. I would just load stuff in the original source currency, to dummy entities or even a separate dummy cube if necessary, then do all the financial manipulation later in regular rules.
