The Custom Consist Editor is much stable now that it was in the past. I have even been using it without the need of cleaning cache (a required step if you wanted to use that tool without crashing ....see past posts on the subject).
It is true I have been using it in past days with SS JR cars and locos, but I believe it will be as stable using old stuff.
I remember you that any consist made with the CE will appear in the Scenario Editor, provided the assets are enabled (with the little cube).
And the usage of an SSD to play Railwork,s will make the assets load much faster.
If you buried it some time ago, just try it again.
