Before I get started, I want to say that the work you have put into this editor is amazing, and it has many advanced features, but at the moment its not very user friendly, and its quite time consuming to work with. I'm sorry if I sound like all I'm doing is complaining, but I'm pointing out my main issues with the editor as it is.
One thing I do not like about the current editor, is that it is very time consuming to complete even a small section of street. Could we potentially get an options page for setting up editor hotkeys? For example, being able to map a macro key to open the properties of the selected spline/helper/terrain former, would be a very welcome addition, and maybe keys for opening the tabs at the side of the editor too. Another issue I currently have, is that being able to drag things around is great feature, when it works. Alot of the time I select the end of a spline to modify the angle of it, the terrain generation kicks in, and I'm unable to move that part of the spline.
The next issue I have is with the object selection - The folder structure of OMSI, for object selection, was great, and maybe its because Im used to it, but this current method is, again, time consuming, especially with the filter in a dropdown. To make this better, you could have a folder structure just like OMSI, with a preview image of the selected object below. Sidenote for the object selection, scrolling down the list with the scroll-wheel makes the world view zoom in and out.
My last issue, is that there is currently no way to change the time of the editor - unless I'm missing something.
Hope that this is some useful feedback, and again, sorry for sounding very negative, as I'm sure blood, sweat, tears, coffee, and pizza have gone into this. If you need me to explain further, let me know.