The unresponsive script problem is fixed in Zoom Page WE 6.2.

With regards to the Ctrl+- and Ctrl++ keyboard shortcuts, iIt depends on whether the page contents are focused or something else (e.g. the address bar) is focused.

If the page contents are focused, then Ctrl+0, Ctrl+- & Ctrl++ will use the user-defined zoom levels or zoom step.

If something else (e.g. the address bar) is focused, then Ctrl+0, Ctrl+- & Ctrl++ will use the standard Firefox zoom levels.