The reason I suggested the signature as I did, in contrast to the suggestion by Lourens Vlaanderen, is that the number of fields that should be auto calculated is probably dynamic and set by some kind of data in the database and thus cannot be added as parameters to the same function call.
Looping the fields and calling RecRef.SetAutoCalcField() for each field would be more useful, IMO.
This is a must-have feature. As a developer, it is more worthwhile to spend time and effort building other functionality for our business than to waste time on workarounds for these multiselect limitations, especially in the case of real-time workflows where a multiselect needs to be used in a conditional statement. Please add this!