From what I understand, the reading/ translation test is pretty easy. Like you, I'm an Americanist who has had 4 semesters of French and 3 of Spanish, and that was enough of the DGS of where I am going (Virginia) tell me that if even though its been a few years, it shouldn't be a problem to pass the test at the MA level and probably the PhD level if I spend some time working at whichever of the two I am more comfortable in.
If you are really worried about it, think about maybe taking an intensive language course. Since I might be doing a little work in transational work with English and French history, I'm going to spend 6 weeks this summer in one of those "8 hour-a-day" langauge institutes. Essentially, you become fleuent enough to translate without trouble and you don't have to worry about it.
If I remember, the Harvard history department has its language exams available online. I remember looking at one when I was preparing my application for there, and it was literally translating a bit of de toqueville.