Unfortunately, I haven't been able to eliminate the JS errors without causing bigger problems (or spending a lot more time on this).
We still have a number of intermittent JS errors, some of which seem to be triggered by DeltaSpike's LAZY mode's use of client-side redirects mid-page when dswid is missing. This sometimes leads to scripts being aborted in strange ways (eg skip signals.js but run crossroads.js which depends on it), which triggers JS errors on the old page just before loading the new page.
We could eliminate at least some of these errors by using DeltaSpike's CLIENTWINDOW mode, but I haven't been able to find a solution for the server-side error "ContextNotActiveException: WELD-001303 No active contexts for scope type org.apache.deltaspike.core.api.scope.WindowScoped" which seems to happen with CLIENTWINDOW when forms are POSTed without a windowId (eg when viewing a project page with stats).
When this is tested, please check on and ZNTA-815, since they are affected by these URL changes.