I feel like emerald upgrades are a good idea but they need more of a structure. Firstly I feel that the enchants should be in the shop at your base to limit people building around these tables and blocking them. Secondly I feel that emerald generators should be back at middle but only used for discounts and upgrades. Thirdly enchants brought from the shop should count to your whole team.
Not sure if the enchants should count for the whole team.
That's how mineplex did it for cakewars back in the day, but there upgrades also tended to have multiple levels, and were more expensive while the game also offered a renewable source of nether stars (equivalent to cubecrafts emeralds) and had random treasure islands spawn with chests that could contain literally anything. Not to mention some upgrades weren't technically upgrades, but effects (for example: boosted regeneration for the teams base or haste effects)
That's the thing: mineplex had a system specifically adjusted for that, and a renewable source of resources that allow you to buy upgrades.
Making enchantments renewable would require the whole system to be reworked again, specifically to function in an environment where enchantments count for the whole team. That's a lot of work:
You'd need to make enchantments in general more expensive for the individual player.
You'd need to adjust the enchantments and their strength in a way that makes the team getting them not have too much of an advantage OR if you do allow a really big advantage, then only as a result of putting a lot of resources together as a team to get those strong upgrades. And you'd need some of the now expensive enchantments still worth getting, for example: I doubt anyone would bother buying efficiency if it was more expensive.
You'd need to adjust the ways emeralds are earned in a way that allows you to get enough of them to get those more expensive upgrades, and probably add a more reliable and consistent source of renewable emeralds due to the higher prices.
You'd also need to make sure the game still gives you an incentive to attack players instead of farming upgrades all game. With more expensive enchants, more time will need to be spent getting the resources needed for them.
That's a lot of work, and I don't think we need such big changes after a big update like this just yet.