I cannot vouch for red/green, but as far as blue/yellow goes the standard client is extremely colorblind friendly after modifications made. Your friend may just be looking for the wrong thing on the indicators. Looking for the shaded center color instead of the high bright boarders is probably what is getting them hit. Perhaps someone with a similar affliction can comment to assist. Is it a learning curve when everyone describes things in terms of color sure, but it is no harder to do once you know what to look for.