Hey everyone, simmer down here.
Let me summarize:
The original name was meant to be a cliched and embarrassing reference to a cat character name, the translator thought "Garfield" would be funny and added in a lasagna reference for the joke of it.
My objection to this is rooted in that Touya is a Japanese character and would not be particular familiar with Garfield (unlike Peanuts, which is a hit in Japan), and that to a reader that fact seems out of place and an obvious "westernization". Replacing with Mr. Mittens maintains the two important facts in the original: It needs to be embarrassing, and it needs to be cliche.
I'm not sure where puns came in but no puns were involved here in this particular issue.
I think the discussion of this particular issue is complete so I'll lock the thread. If you find other issues you think are overlocalized, feel free to mention them in their appropriate series/parts threads and I'm sure the translator/editor will give your opinion due thought.