Service event_subscribe before path_processor_inbound I have ha service with tag: event_subscribe (KernelEvents::REQUEST) with priority 30 and in the same module a service path_processor_inbound with priority 29

The problem is: in event_subscribe Service creo a Constant but the service path_processor_inbound is called before.
I tried all the variants of priority, but it is not the problem.
Both priorities are for different queues. If you set a priority for an event subscriber this is only for the specific event you subscribe to. In this example you subscribe to KernelEvents::REQUEST. Then you can only move up and down in the list of all other subscribers to this event.

You can find more information and a list of the D8 events here:

https://api.drupal.org/api/drupal/core!core.api.php/group/events/8.2.x

Path inbound/outbound processors are not even events. These are handled by the PathProcessor Manager and the priority set here is again only for the list of all other path processors.