You can override a URetainerBox which is a widget that already renders to a rendertarget for a delayed presentation, then you can use that render target for the spectator screen custom texture in the Eye + Texture spectator mode.
Using the widget renderer itself is also fine, but you can still just use the Eye + Texture spectator mode, skip the scene capture 2D unless you are specifically trying to have a second custom view.
I didn’t look too much at your code since it is obvious not formatted correctly…there shouldn’t be a memory leak normally unless you aren’t clearing memory you allocate though.
renderer = new FWidgetRenderer(false);
Couldn’t find where you release this again in trying to scroll through.