Hello Iwans , I try to download this template but the link does not work, you could send the link to download it please, thanks good job with the theme we Chocoloate 1.5.x.
I was willing to test this theme but once the file listed here is downloaded it all contains a text file linking to the author's site, thus why don't invite people to visit the site directly somewhere instead of uploading a tricky file.
The last release of this compatible out of the box with Elgg 1.5 not Elgg 1.7.X.
Those errors are generated because in previous versions those fields where not mandatory. To fix this you should to look up where the link is generated and call the elgg_add_action_tokens_to_url function to add those parameters.
Actually I'm not working in this plugin so any patch it is welcome
I abondend de development of this plugin some time ago. For similar features you can check: http://community.elgg.org/plugins/736791/2.4/group-tools
However if you need some customizations for groups (or another plugins) I can help you working as freelance.