the damage to the vascular tissue is causing the plant to have trouble providing to the entirity of the plant.. may also be causing a drastic reduction to hydrostatic pressure too. So, it may shed some leaves even if in the process of healing.
i'm not sure burying it is best, but hte other stuff you did to mend it is good -- tape is good to use, for example, or propping it up so it doens't stress the damage etc. (dirt could infect the open wound with its numerous microbes, if it'snot going to disturb it, i'd brush that off, but at this point it probably doesn' t matter.)
give it time.. it'll heal or it wont, but you have to give it time.