For reporting, the only options are to use UDFs or to expose columns. The use of UDFs is not recommended for production, so your only other option is to expose them. If you have columns exposed that you no longer need, I think you may be able to drop the column from the table, then resave the class and that should tell Pega to stop trying to populate it. I would test this before trying in production.
If you're trying to expose and populate more properties and it's failing within Pega, that may be something we can assist with if an SR is entered, depending on what the underlying problem is. Could you provide more details about what is preventing the column population job from working properly?