Selling church property
If a WELS church sells their current building because they are expanding and building a new facility, but they sell to a church that WELS feels preaches false doctrine, is that wrong? The church made a profit in the sale to the Unitarian Universalists. We are taught that bake sales, pork dinners, salad suppers are wrong because it brings in money from other sources, but isn't selling a building to a church that teaches false doctrine also wrong? Profiting from outside sources?
The real estate transaction you described would not be wrong. The scenario you described is that of a congregation relocating to a new site, necessitating the selling of the facility they no longer needed. If their assets—especially the land value—increased over time, then there was the potential to sell at a profit. Selling to another church, even a false church, would not be wrong.
There is a difference between a one-time real estate transaction and the other kinds of events you mentioned that might take place regularly in a congregation. It is possible for the congregational events you mentioned to give people the impression that the church cannot support itself financially and needs the financial assistance of others outside the church family. I would not equate the selling of church property with fundraisers that seek community involvement.