There is not full mod support, there is still much to do in order to take a mod from EM4 and make it work in EM5, the systems are pretty different especially for models and maps. Let's be honest that is the bread and butter of most mods out there, so you're looking at an incredible bit of work. I am not sure how the scripting aspects work in EM5 vs EM4 at all, so I can't even fathom what would have to change to make that work. Simply put it's not something we have in mind to do with regards to this mod, all of the effort to this point was to make EM4 gameplay more evolved as opposed to trying to make the game look prettier (em5). As framework aspects go, we would rather stick with EM4 rather than trying to go into EM5 and
probablymost likely have to redo 90% of what we've done thus far.
Their SDK has been released for EM5 yes, but as to improved function/performance/gameplay that has not been proven yet, this latest "patch" (they call it a DLC I call it a patch) just came out and as far as I know nobody has really worked with it to see what it actually does/is capable of doing. Don't try to put the cart in front of the horse with figuring well they released some tools, so now it must be a cakewalk to just flip everything over, chances are it is not going to be that easy unless someone makes additional tools to make it possible. I myself don't feel like going into EM5 is really worth it for the step backwards in game play that I experienced in my trial of EM5, my fellow cohorts would have to speak for themselves as I can only speak for me, but I was unimpressed with EM5.
Acutely the patch was just released for people with cd. Steam user are still waiting. Since the game still on sale for 22 hours I bet the steam version get delayed till after the sell. Which tells me the patch is just more talk and no action.
There still hardly any document on this mythical editor. I notice they wait to release the patch to CD users (who are likely germans as I have not see any box for the game) Till after the close of bussiness in Germany. In fact I do believe the release came out around 10pm in germany. Ie last minute so they can say the patch came out in Feb.
Where it be release to steam user much later. Likely after the sells up. So when every finds out that yet another patch did not fix the issues. It would not hurt the sales of there fire sale.