FCP checks the template supplied vs what is actually running. Those ports are specified in the template, but do not exist in the data structure about the container itself.
Or put simpler,
In host mode, there are no mapped ports. Doesn't matter if they appear on the template or not (and they probably do). They do not exist in a mapping. Assuming that you still have the ports displayed when you edit the container, your can change the host mapping for port 5050 all day long, and the container will still only respond to port 5050 due to the host setting.
or to put it another way,
FCP tends to highlight stuff that trips people up. Ultimately it comes down to
My opinion, and community members on what is right / wrong based upon various threads around here.
In the case of anything app related, the maintainers of the app's template that dictates FCP's analysis.
Some of the issues which are tagged as errors / warnings will not actually hinder the operation of your server / apps, so long as you know what you are doing. This is one of them. (Although I honestly can't think of a valid reason for switching from bridge to host - at least not for something like CP)
You have a point that its a bit redundant in this case, but the errors are valid. If you want to run the container in host mode, then ignore them all.