I dont think I have heard of achievements before…  We do have a simple press cubepoints plugin to achieve integration with the cubepoints wp plugin so it will be much more compatible than the achievements plugin.  without a simple press plugin (or at least some written code), that plugin wont know anything about simple press nor award any kind of points for forum activity…

There is a question currently as to whether wp cubepoints is abandoned or temporarily offlline.  Another user recently recommended a new plugin that was developed to replace cubepoints call myCred (https://simple-press.com/support-forum/ideas-feature-requests-and-next-version/plugin-for-mycred-cubepoints-replacement/)…  we have not had a chance to look at it yet…

If you wanted to give us a link to this achievements plugin, if we need to develop a replacement for cubepoints, it could be considered..  we also offer a custom plugin development service…