There are a lot of things about "Eichmann" which seem curiously wrong. For one thing, this Eichmann is a lot more interesting and colourful than the real man appears to have been. There's a bizarre scene in which he is challenged by his very weird Hungarian mistress to shoot a baby; I won't give away whether or not he does so, but it's not something I've ever heard of before. This Eichmann is a womaniser, a bit of a boozer, altogether a more louche and raffish figure than the rather dull bureaucrat that I've always read Eichmann described as.
Yes, the film suffers from some weird accents. Thomas Kretschmann, as Eichmann himself, speaks in a clipped German accent; Troy Garity, Franka Potente and Stephen Fry (in a bizarre but oddly convincing performance as, of all things, the Israeli Minister of Justice) all have indeterminately foreign accents, and none of it really makes sense.
Having said that, Kretschmann carries off the job he has been asked to do, and Garity is really very good as Avner Less, who was not Eichmann's prosecutor (as someone else stated) but his interrogator. Less was not a lawyer but a police officer. The subplot of his wife being chronically ill is presumably there because it was true; it would have been better if they'd left it out, because what drama there is in this film is the battle of wills between Less the dogged interrogator and Eichmann the stolidly evasive interrogatee.
I note in passing that Stephen Fry might almost be the rather more well-fed first cousin, or perhaps uncle, of Ciaran Hinds in "Munich". The accent is the same, and the tallness, slicked-down hair and intimidating bulk is very similar.
If they'd toned down the lurid stuff about Eichmann's sex life and focused on what he actually did for a living, this could have been as good as "Conspiracy". Pity.