Sounds like a poor quality de-brief and as mentioned the quality of the written report is not great. Also I rarely offer advice at half time as it can produce a conflict within the referee as they try to incorporate changes within properly digesting them.
Starting off at the top of your comments...
A solid performance is observer speak for not doing much to impress. As I've said elsewhere, we can only mark what we see, just as you can only referee what's in front of you. In a "solid" game, there's little opportunity for the referee to demonstrate what he or she can actually do. In games like that, there is more opportunity for little things not being one correctly standing out and having a disproportional effect on the report and mark. It means that unless something happens that allows you to clock up marks, all you can do is lose them.
Getting caught in play is something I am seeing more and more at L4 (saw it at 2B recently). It's mainly because referees are scared of missing something, so they close down on the action and as a result either compress their view (losing their peripheral vision, which makes it harder to use the trailing eye) or they collide with players and/or the ball. The solution is simple, just push further left, out to the touchline if necessary, to get the angled view of contact in the challenge.
As for the "flashed" card, this is a big no-no especially as the procedure is set out in the performance criteria. Looking at your report and your additional comments, you seem to have had a nothing happening game in which you had little opportunity to clock up marks to counter those lost for little things. It seems that at least one of those may have been your observer's foibles.
