How plausible would it be to modify this 1.20.4 custom boss bar datapack to work on 1.20.1?

I'm not sure how to go about this, but could someone point me in the right direction on how i could modify this datapack's code to get it working on 1.20.1? or would it be not possible alltogether due to the lack of some feature added in the newer versions?
https://www.planetminecraft.com/data-pack/custom-dynamic-souls-like-boss-bar-utility/