The CERM wouldn’t help at all. The SERM is kind of an okay study material, but I actually opened it maybe once for like a retaining wall question or something. SERM may help you get more familiar with the codes though if you aren’t with most other than AASHTO.
For the most part, you really do just need the codes listed, because they questions for the most part can be answered from them. NDS, TMS, ACI 318, ASCE7-10, Steel manual, steel seismic manual(2nd day), etc.
They just ask an obscure question, and you have to know the code like the back of your hand to get the answer efficiently. The topics are much more advanced compared to what they ask in the PE as well, so you really have to know all the important little details required.
If you were to compare the PE exam, in my opinion- the PE tests general knowledge on civil engineering, with a minor focus on structural. Yes you need to know basic concepts, but the small minor important details are ignored and if you are close, good enough!
The SE, you have to know EVERYTHING.