This is the primary community forum for these types of games. If there is a specific "CosmoK fix," there is almost certainly a dedicated thread there where the developer or a trusted modder has posted the changelog and the file.
Most creators (like the team behind Melissa's Adventures) post their latest bug fixes and version updates directly to their supporters first. melissas adventures ch1 v5 by cosmok fix
To get the most legitimate version of the Ch1 V5 fix, you should stick to the official community hubs. This ensures you aren't downloading malware or outdated fan edits. This is the primary community forum for these types of games