Certainly, thank you.

It reminds me to do something with: https://github.com/AlexanderOlkhovskiy/0ad-space 

Perhaps theyre suggesting this hypothesis? https://en.wikipedia.org/wiki/Nordwestblock

@razieve thanks for reporting this. I can confirm this is a ModernGUI bug on the development version.  A condition was poorly written which created this ghost foundation in some edge cases. It will be fixed next time I push my local work. In the meantime you don't have to worry about it affecting your game. This foundation placement doesn't consume any resources, nor creat any obstruction of any kind. Basically it doesn't affect anything, but you can still delete it to make it disappear. If you want, you can also enable 'global queue' feature to make this work, where builders will start building the foundation once the required resources are reached. 

Sounds like something that should be handled in vanilla and not require mods to implement the logic. You should open a issue for it, I might pick it up myself. If you do, attach a dummy template of boat with turret point to make the testing easier. Or if you can't wait next release and you just want to do it yourself, please open a PR on main repo that would be most useful.