Too many commas?

I think his use of commas is fine. There are sites which outline the use of commas in detail. If I remember correctly, there are 11 reasons for inserting a comma. Here's one site:

https://businesswriting.com/business-grammar-training/rules-for-using-commas/

His commas are fine. But I would omit your comma after "in some cases."

What they said. ^

I agree with what has been written so far. Is this a technical manual or literary publication? This will make a difference.

If it’s a corporate professional situation, you must know that your editor is bound by a few parameters besides punctuation technicalities. He is the arbiter of an agreed upon corporate or “house” style. If he wants the added commas, give them to him as he’s not wrong. Not sure how it slows the reader down. He may feel it provides a pause for clarity.

However, if this a novel or some literary publication, it is less stringent. You can debate this matter, but as an editor he’s paid to advise you as he sees fit.