In the past, Construct did not correctly validate the names of all items in a project. For example it'd incorrectly allow characters not allowed in filenames, s...
For an engine willing to deprecate or destroy plugins to "prevent" a "possibility" of future project breaks through Addon SDK v2, you sure do lots of project breaking updates.
I find it ironic that the goal of Addon SDK v2 is to prevent project breaks by breaking projects with plugins. But when it comes to your updates breaking such projects, you have no regard for them.
This is nothing to do with the Addon SDK v2 - the situation here does not involve addons at all, and I think it's unhelpful to try to bring it up where it's not relevant. Projects using valid names are entirely unaffected by this, which we believe is the vast majority of projects. Projects using invalid names were already broken in certain ways, such as being unable to save folder projects; trying to frame this as us breaking people's projects is also unhelpful. Even though we suspect there are few affected projects, we are taking steps to comprehensively document the changes and help people update their projects - I don't think anyone can reasonably claim that means we have "no regard" for them.