Thank you for your feedback! Your points are absolutely fair, and I feel that I should address them:
1) and proximity part of 4).
At this moment, I do not want the make a total conversion and pre-generated Honorverse galaxy. That means that for generating Yeltsin and Basilisk (and potentially other systems, including Manticore B if we go by the two star solution) I use the same method that is used for default Sol and Deneb systems, i.e. generating a "child" system at the certain min to max distance. However, as far as I can tell, there is a major flaw to this method - it does not actually create a star system, it just picks a star system within the range stated and changes it to the "child" one. Therefore, if there is no applicable system in range, the "child" system will not be created.
I actually tried doing Manticore Binary as two extremely close system at first using this method, but chances that your starting system will have another one really close are slim, so it worked like 1 in 20 tries. I found not solid way to actually create a new star system at the moment. If there is one, I'll seriously consider remaking Manticore.
Also 1)
Regarding asteroid belts: Yes, I absolutely recognize their importance for Manticore, but I am indeed limited by the way the system is setup. Binary I created is a workaround, where the central "sun" is empty, it is orbited by two "planets-stars", and those are orbited by the "moon-planets". This method, however, has certain problems. There is no way to add asteroid belts to planets and moons to moons. However, I thought about adding several single mineral-rich asteroid to orbit "planets-stars" to emulate asteroid belts, and I may do so in the future.
1), 2), 3) Planets sizes and modifiers.
I absolutely agree with you, and some of these are already addressed in my WIP update. I wanted to create systems first and add detalization later. Some of it is already present (like alien pets in Sphinx, although it may not be fair to describe treecats as such).
As for Cecitiel, I have no idea where it went. I remember adding it with other planets, but I may have deleted it by accident. This will be fixed for the next update.
5)
Government and ethics are the biggest problem with Manticore at this moment. I also believe that they are a big problem with the modding as a whole. Stellaris HEAVILY relies on existing governments and even more on ethics for the handling of events and policies, and most of those do not have "default" response. You can see the example in the first page of the thread with "Birth of space piracy" event. That means that adding new ethoses is a huge pain in the ass at the moment, and requires a lot of work with existing events.
As for the -10%, this is a stupid oversight on my part and I'll try to mitigate it as soon as possible.
Anyway, reworking Manticore government is high priority, but at this moment I'm just not exactly sure how to proceed with it.
Thanks a lot for your well thought and formulated feedback, I really appreciate it.