We need this as well. We reported a bug in exportcolumn two years ago...(It was only re-reported and fixed later in the https://github.com/varigence/BimlPit/issues/138)
But we're still waiting for "the next release", now more than half a year later!
Releases need to be more often than yearly!
I'm trying to convince my department to use BIML, but it's kind of hard when we can't even make a basic example without errors in the resulting packages.