I understand what you mean, but I don't think I agree with you. You are defining the compound noun "Accumulation space". The definition of this compound noun includes the word "accumulate" because that is what the space does. The definition of "Accumulation space" does not (in my opinion) need to define the word "accumulate". "Accumulate" is a verb that is easily found in any dictionary.
To give another example, "swimming pool" is also a compound noun. A definition of this noun would only rarely define "swimming". A definition of "swimming pool" may try to define the word "pool" because the word "pool" has multiple meanings.
Do you think either of the words "accumulation" or "space" are ambiguous enough, or have enough multiple meanings to require a definition?
In my opinion if the designers want to be more clear the best place to give a definition of "accumulate" or "space" would be in the rules or the compendium, not on the card.
Accumulation space: something that accumulates goods and food
Goods: All building resources, grain, vegetables, and animals ( is this correct?)
Building resources: Reed, Stone, Wood, Clay
Animals: Sheep, Boar, Cows, Horses (except minor improvement horse and) ( lamas
Accumulate: to increase goods or food by successive addition
space: Any action space on the board, also any space added to the playing area by any card.
Ok, I hope this is clear that I am trying to be helpful, not just trying to have an argument with you. If I had a better phrase for "accumulation space" I would tell you, but I honestly think the phrase you have is good.
I wish the best success with the revision, not least because I always want the best playing experience.