Doesn't look like much green there, hope it lives. You are coming into winter, cool weather. It most likely is Bucida, if the seller said black olive. Which means it does not tolerate cool or cold very well. Growth will slow to a crawl or stop altogether if temps drop into the 40's.
Second, I would quarantine this freaky thing. Knots on roots like that are often pathogenic nematodes. They spread through soil and water splashing off the soil and down onto a neighboring pot. This problem could spread. I know of no pesticide that would kill the nematodes and leave the gall and tree alive. Incurable except by eradication (burning the galls & roots) and soil sterilization, either chemical (NaSCN or NH4SCN)) or thermal.
An alternate cause could be gall wasps, which would likely hatch out sometime in spring, and possibly attack your other trees. Here a systemic like Imidacloprid would kill the wasp larva if they are still feeding.
While it looks ''cool'' bringing likely diseased trees into ones collection requires additional precautions to prevent unintended spread of the problem. Not saying you should get rid of this, just offering that you should be careful with it. Allow not soil from it, to get into any other pot.
Plant virus are another issue, while I doubt this is a virus, I seldom bring ''variegated'' plants into my collection, especially variegated plants that are rather ''streaky'', as often these are plant viruses which can be spread by cutting tools and sap on human fingers. Bold, clean variegated patterns with sharp margins between colors are usually epigenetic mutations, and are not communicable, are not a virus. These are safe. But fine streaky variegation, especially accompanied by little spots of sunken tissue or necrosis are often virus.