Columnaris feeds on temp and uneaten food. You need to remove all wood and decorations until this is rectified. You need to clean the gravel thoroughly under these items that you removed. Lower temp and treat. I have a friend that has something that is similar. He tried everything, nothing worked. He is currently treating with TMP Sulfa from National fish Pharmaceuticals. He is treating daily for 10 days with a 40% water change, and 1TBL salt/ 5gal. His fish are clearly better today than they were 2 weeks ago. He still has 6 days left on his 10 day regimen. I would get on the computer and read. First in the Bifa's mouth then on the fish, sounds like columnaris to me.
Remember lower temps and thoroughly clean the gravel, and daily water changes.
Remember lower temps and thoroughly clean the gravel, and daily water changes.