Currently the colours of hearts range from black (0), red (vanilla), orange, yellow, green, blue, purple, magenta, pink, light yellow, cyan, light blue and then white. Currently everything up to and including blue is covered by the mod; it would be helpful if all of the higher hearts also had item and canister equivalents added as well for modpacks and other stuff to use.

well you can just increase the maximum stack size for heart canisters in the config. Heart canisters don't really correspond to how mantle colors health rows, anyway, as you could for example only use green hearts, but get orange ones in your hotbar since they would be the first 10 additional hearts.

I think having more of them would be better looking for progression and stuff in modpacks though, since you might still want a limit of 10 per canister and force players to unlock the higher tier canisters to get more health beyond that.