I have a login system on my site and I want my users to upload avatars they want so these avatars can be displayed on the commenting system. If there are no logged in users then show default image.
Does your site already have the ability for users to upload their avatars? If so then it wouldn't be difficult to integrate that with Commentics and I could provide help with that. If your site doesn't have that ability and you're asking for me to build it, either for your site or for Commentics itself, then yes it's beyond the support of the project.
For it to show a broken image and not a proper Gravatar suggests to me that the URL is not in the right format (see below example of correct way). So viewing the source of the URL will help you to determine that the URL looks like it's meant to. By this I mean for example that there is no error message where the $email variable is hashed and where the $gravatar_parameter variable is added. If it looks okay then try copying the URL from the source and pasting it into the address bar of a new tab to see if the resulting image is still broken and whether you can notice anything wrong.
But if the only reason you're using the Gravatar URL is to show the default image then it may be better and faster to serve it locally. So maybe just download the default image and include it from your site similar to how you're doing it with the avatars.
