Gents, as this is a matter close to my heart, is there any way of getting a change so that a PPL FI without passes in EASA CPL knowledge exams can teach a PPL?
You've got people getting trained on their FI courses to the exact same standard, regardless of whether they have CPL exam passes or not, and who pass the same test to be allowed to obtain their FI rating. Plus, as previously mentioned, a load of the BCPL crowd from years ago are happily teaching PPLs, while their modern counterparts are stuck to teaching LAPL/NPPL for the foreseeable future. So either pull people's (B)CPLs and downgrade them to PPL FIs (either with or without CPL knowledge) with the relevant instructional privileges, or just accept that an FI is an FI, and can teach a licence that they have themselves. Perhaps only bring in a CPL requirement to teach at that level?
If it's an ICAO compliance argument, then just get people to take the FAA commercial pilot written at Farnborough, and hey presto they now possess ICAO CPL knowledge, and haven't had to spend £1-3000 for a distance learning course, 6 months of study, and 2 weeks stuck in a classroom miles from home with all the associated accommodation costs, while taking time off work to pass a large amount of exams which lack relevance, cost more money, and have to be taken when and where the CAA deem fit.
To answer the OPs second question, no, because having the ratings alone, only allows you to do them yourself. To teach them, you have to lift the restrictions from your FI rating, which entails further training, and most likely expense to the CAA to add the new privileges to your licence.