As to the physiological response from the plant, you are probably ok unless you have a particularly harsh winter in which case you can expect dieback on the new growth that will be forthcoming.
As to the pruning itself, I am sorry to say I don't get it. I can't figure out what your plans are for this plant. I abhor all the parallel branches on the left and I think the opposing branches further up are going to be a problem. Cuts themselves look a bit jagged as though they were done in multiple stages. I don't know how the plant will react in that regard. I have very little Japanese holly experience as bonsai .... actually none. They don't interest me. Maybe someone else will pipe in who has experience with them.
Good luck. I don't really remember what I was doing exactly 40-50 years ago, but I am sure I did things worse than this to my plants.