I've added a first draft of the file checking. So far it only checks Mongoose trade codes, but here is a snapshot of the current version, along with a file. I've not double-checked (hey, it is 5:38 in the morning!) but my guess is that this is the only incorrect line.
The things it checks for the trade codes are the number of lines (and this would only be a warning, not a breaking deal. I do plan on adding a column for passing the checks) (and this is only valid CSV lines, it ignores the headers & blank lines) and that there are 10 items per line.