I think that it would be better and easier if there was one cultivator for every plants, like the space cultivator, instead of one for each plants.

So 100% that would be better. However there is no ingame way to ensure that that one cultivator will obey the placement laws of the plant. There is that setting that removes placement laws, and I could make it so that when that is active, we just use 1 cultivator perhaps.

Do you play with that setting on? I know most people would only play with that setting due to too many modded plants being added (and thus too many collision layers) for the game to run, so they need it to run the mod. I consider it too easy to play with unrestricted cultivator placement.

Another small issue is the graphic - I don't think I would be able to kitbash together the correct tree into the sprite if the cultivators were the same =(

(and I reeeeaaalllly like the individual tree auto graphic =P )

You could alternatively use a different sprite for the cultivator, something similar to the space cultivator.