It looks like you are using multiple golems, or with a range upgrade with the golem. My setup I had used only 1 golem and had practically every block in a 4 block radius (9 x 9) filled with mana beans. Your farm does look nice, but it is using an 6 block radius for the farm (13 x 13 for the beans)
Well... technically, they have the same size! You have a 11x11 structure and you are using the internal sides for the farm, giving you a 9x9 farm. That is the reason of my post, with the same 11x11, I made a 13x13 farm using the outside sizes of the logs and having no problems with the beans getting stuck over the logs!
About the number of golems, I have 2, like everyone else. An harvester and a gatherer. Both flesh golems. Gatherer does not need an upgrade. Harvester, not sure. I had an upgrade initially when I had other problems and a different setup and never removed the upgrade. It might not need it but I think it will.
But, golem and upgrade cost is indifferent. The objective is making the most efficient mana bean farm in the long term, so the cost dissipates to zero with time.
The only important point is the way beans are placed for max output and in a 11x11 structure, using the outside side of the logs is more efficient!
I also complement this farm with a grinder and a auto-spawner with Forager's
I noticed the bean farm tends to have a much lower chance of giving some beans . Like, I have 1000 aqua and only 150 Instrumentus.
Foragers, on the other hand, usually give the rare beans and not the common ones, so its a nice mix. Mob essence farms with cursed sand and grinder will keep the auto-spawner running.
Again, this is thinking long term and having an infrastructure that gives me everything I might ever need in the long term.