In the case of CEP, we use the latest version on Higher Ground, which should be backwards compatible with any servers running previous versions of CEP. Given the difficulties you mentioned in the previous thread, I figured I would point you in the direction of the ARF2 installation tool we use that will download and install CEP for you. I've written an installation guide that walks you through the usage of ARF2, which you can find
<span class="podkreslenie">here</span>.
Simply get ARF2, and you'll find the default update options are just to install CEP if you are missing it. All of the other content is optional and unnecessary if you don't intend on playing on Higher Ground, so you can simply delete ARF2 when you're done with it, if that is the case (or keep it around to make sure your CEP stays up to date).
One warning: The CEP files that ARF2 downloads contains the cep_custom hak specifically for Higher Ground. If other servers have different cep_custom files, you will still be able to at least join the servers (you won't get that error message you've been getting, unless they use
additional custom content that you'll have to search on the web to find, download, and install), but you may find yourself occasionally crashing when the server asks you to load content that doesn't exist.