Are you saying that the +100 wizard guild workshop bonus is incorrect?
While I didn’t test ‘public workshops’, this is the value I was able to confirm for the wizard guild workshop on multiple tests well.
I assume you’re both comparing the difference from a non-node to a guild workshop. If you compare the number to a node vs. a guild workshop, you should be able to get the determine the actual number. This is really getting into semantics, but being on a node doesn’t provide a bonus, instead it actually prevents a penalty (for not being on a node). Not a huge issue, but if you do incorporate the non-penalty into the guild workshop bonus, it also needs to be incorporated into the public and private workshop bonuses. But when I said the private workshop bonus is twice as effective as the public workshop bonus, I was not including the negation of the non-node penalty.