Translator here. Assuming the report should be
- the truth
- the whole truth
- nothing but the truth
my first instinct when it comes to expecting a false report is to look for violations to #3 (i.e. lies that "adulterate" the truth, hence my word choice), while it seems that yours is to assess #2, to look for omissions.
As far as I can tell, Ferdinand expects the agents to modify their report in some way to suit their own ends, though whether that means omitting details or straight up lying about things, I can't say.