Admin Errors – Plugin not working

I took on a site recently using the events plugin, however the plugin’s settings/theme pages are broken and the frontend shortcodes are not working.

I am getting errors on the admin side when the plugin(s) are enabled, also have extended views):

Query monitor:
php_uname() has been disabled for security reasons

Inspector console:
Uncaught SyntaxError: Unexpected token <
https://…/?ai1ec_render_js=less_variables_editing.js&is_backend=true&ver=2.5.28

Also there are update/disable notifications stuck:

The add-on “All-in-One Event Calendar Extended Views by Time.ly” has been disabled due to an error:
The add-on All-in-One Event Calendar Extended Views by Time.ly must be updated to at least version 1.1.3 to maintain compatibility with the core calendar.

Using latest versions: 2.5.28 and 1.2.11 for extended views

Please assist!

The page I need help with: [log in to see the link]