What feature do you want to see added?

There is a feature in minecraft since 1.16 for the nether update where you can have soul fire on soul sand and soul soil, but I think it would be nice, if we have an option in the heatray brush that allows builders to also set soul fire if they want to.

Are there any alternatives?

Well you might need to replace them with FAWE if possible, that would be one more step.

Anything else?

Just had the idea while experimenting