So Mitt Romney is literally going to Israel to fundraise?
Yes. It may be included in a Romney campaign ad, because it shows how he's friendlier with Israel than Obama and voters like that nowadays. Certainly it'll be something Obama tries not to mention.
I seriously doubt Mitt Romney will make a campaign ad bragging about all the dollars he's raised in foreign countries.
Mitt Romney will be able to use that fact to brag about how much Israel supports him and how Obama betrayed Israel, though you're correct it can't literally be about how much money he raised -- just about how he talked to people and what their opinions are. And certainly Obama won't use that line of attack because he is desperately trying to look pro-Israel.
In American politics, Israel is very much a special case. The rules are different.