Jeholornis was certainly a seed eater, and I wouldn't be shocked if Jinfengopteryx was (although I would be suprised if "Jinfengopteryx" is actually different enough to be separated from Sinovenator). But niether is a climber, and Jeholornis was not landing in trees. WAIRing up perhaps. Same with Microraptor (i.e. not climbing up tree trunks).
In South America there are frugivorous fishes (like _Collosoma macropomum_, known as "tambaqui") - as far as I know they do not climb tree to get their meal.
[]s,
Roberto Takata