Avoiding Inner Platform

[gamyers]

I'm just asking "How could I accommodate a mutable schema without implementing it the way Jira did?"

Are we talking about an application you are writing ?

One option is go Open Source, so if the customer wants new columns, they adapt the application.
Another option is, if the customer wants new columns, they pay you money to add them and customize the application accordingly.
Third option is, work out all the possible columns and build them into the application in the first place.