Force language based on subfolder
Currently you can only set the language with ?language= GET variable and then a session cookie is used for further pages. This means that search engines will only see the default language as they don't support cookies, it also means that you can have the same url have different language content.
We NEED to change this.
We need the ability to force the language using a sub-folder for each language e.g. domain.com/it/ (this could be a simple mod_rewrite rule) but whmcs needs to then detect and then serve the correct language as well as generate the urls to include the sub-folder.
This will make SEO much easier and all search engines to index all language content so all our sites and especially KB articles will be properly indexed and much better if it was a built in part of whmcs.
I have managed to achieve this on servwise.com using a lot of mod_rewrite and a heavily customised template (perfectly in v5 and in v8 to about 95%) but your new v8 functions that parse some pages through the index.php give a 404 error if you rewrite the base whmcs url.
At minimum I would ask if you could resolve the 404 error when rewriting the whmcs home folder.