When an OFX file containing multiple accounts in it is imported in moneyGuru, only the last file is read. There's a sample OFX file at https://gist.github.com/hsoft/6334109
I've analyzed the code of /core/loader/ofx.py file. I think the problem comes from function end_stmtrs which will only work properly if a BANKID and BRANCHID are defined with the ACCTID in the file. But, as you will see in the sample file, there is no BANKID nore BRANCHID in the credit cards transactions. So I think it shall work better if you remove "hasattr(a, 'ofx_bank_id') and" on line 68 of this ofx.py file. This way, if I understood your coding, you will switch to a new account even if there is no BANKID associated with the ACCTID.
Hope this helps.
Improved OFX parsing
The problem was rather that it didn't count CCSTMTRS as an "account starter" tag, and it messed up thing.