Premiere’s new layered drawings are not in the Project panel
I haven't really tested the new Type and Essential Graphics functions yet, but I've played around with them a bit and I think I have grasped the essential functionality.

The text I create using the new Type Tool or graphic tools doesn't show up in the Project Panel for me either, as you described, so it stands to reason that this is the expected behaviour. I can't tell you why Adobe decided to build it that way. I can only assume it is to avoid visual clutter. The old functionality where you had to create one Title item/asset for every text insert in your video was indeed a bit clunky, so I would assume the new graphic items don't show up in the project panel to avoid cluttering and streamline the process. Also, having each graphic/text item appear in the project panel would create new design problems; for example, where would they go? If you prefer to have all your graphic/text items in one bin, do you have to sort the newly created items into that bin manually every time? Also, what part of the formatting/positioning is retained on the asset and clip basis respectively? How are point and area type handled respectively? And what about one graphic using multiple paths, how would the program discern between individual items and stuff that belongs together? 

Again, I can only speculate as to what lead Adobe to make that design decision. If you don't like it, you can always contact them and ask for an explanation or for a change. Personally, I think I prefer a clean project panel over having it cluttered with myriads of individual path/shape layers, but that's very subjective I guess. 


  What I want to do is copy elements from one timeline into another (many Acts in a single performance). Normally I can just copy/paste or equivalent mouse gestures from an expanded tree view of the Project panel in list mode. 


I found two workarounds:


You can just select one or multiple clips from the timeline and copy them by pressing CTRL + C. Then move your playhead to where you want to paste them (in whatever sequence you want to paste them into) and press CTRL + V to paste them. Note that you can control what tracks your pasted items will appear in using the Track Targeting toggles. 
You can select one or multiple items in the timeline and nest them into a sub-sequence using Right-Click → Nest…. The nested sequence will show up in the Project Panel and can be reused from there. Changes to the nested sequence will be applied to whereever you use that sequence as well.