As it isn't mentioned that clearly in the documentation:
1. Can I run delta checks if jolokia is used in proxy mode?
2. If so, should the delta seconds be set the same as the check_intervall? Is there any kind of relation between this values?
3. Do I have to enable historic values within jolokia for beans which I want to check with delta?
Delta checks are mainly a client side feature of check_jmx4perl, the only server part is that the previous value read is stored in the agent's memory. That should work also for proxy request (its a generic mechanism). If not we should have a closer look. Please open then an issue on Github, preferable with a example setup which we could to reproduce it.