Wow, 4 hours of boiling wood, guess it must be hard boiled by now.....
Must mention that I have never boiled wood at all, a good scrub with a small wire brush and pour a couple of kettle full of boiling water to rinse it if and help to get rid of any nasties.
You mention you dipped the plant. In what? Bleach/peroxide? Hope this was diluted with water but Anubis are pretty hardy plants so hopefully it should be fine.
General rule of dipping is a ratio of 19:1 water to bleach. Some plants will not be able to survive a dip in undiluted bleach. Oh and you must rinse the plant well with water after the dip, you don't really want any bleach in the tank water.
But the tank looks good and lovely light coloured betta you have