If a repo uses properties from the other repository "other" I should be able to find that repo's property P2 searching for either "other:P2" (works currently) and "P2" (does not work so far).

In case there were multiple repositories providing the same entity type (theoretical for now but might be needed in future) searching for an unprefixed ID should return matches with the given ID from all repositories where such a P2 exists. Special case would local and "other" repositories providing properties. In such case while searching for "P2" results should contain both local "P2" and the "other:P2".