As pointed out Hashem doesnt have emoions. We attribute our emotions to Him in order to relate/understand. We percieve Hashem as being Angry etc. In which case I dont get the question if you percieve something coming from Hashem (and everything does) as being humurous then Hashem has a sense of Humor.
Heres a (not great) example. I’m sure all know the classic joke of the Reform Rabbi who goes golfing on Yom Kippur and gets a hole-in-one. The Malachim ask God How can you allow this when the Rabbi is desecrating the holiest day. God replies: Who can he tell.
Now whether or not the joke is funny, is it kefira? Since it is attribuing an emotion to H”KBH?
More to the point though. Suppose the story was real, namely the reform Rabbi is golfing on Y”K and gets a hole-in-one. The Rabbi “gets” the joke and is annoyed at his hole-in-one since he cant tell anybody. and views it that way as if Hashem is “playing a prank” on him. Is that view kefira?