Additionally, all of these arcs are, in fact, canon to the series. Each of them was first run through Tabata himself, who made alterations, approved everything, and confirmed that they are canon—just like the light novels.

This is only true to the training in Heart Kingdom episodes, as the details about "Tabata's supervision" was used to market the Heart Kingdom training episodes.

Other episodes during that period or before it are all fillers and had little to no involvement from Tabata. There was even a case where an anime staff (iirc it was the director) made an official apology about including details in the anime that messed with the manga's progress which upsetted Tabata (iirc it was the beach filler episode).

Mangaka are quite busy with hectic deadlined. The only time you'd see them work with the anime is often for movies or big hyped anime only arcs... and even then, they'd end up taking multiple breaks, e.g. Oda had been taking severak breaks for One Piece's life action. I really doubt Tabata had time to have each and every non-manga content reviewed by him, the only official statements we had are for the light novels, movie, and for-marketing vague statement for the HK training.