I didn’t even think of combining zeek and spicy via get_value. It works much better with your solution. But it still has a limitation: If the zeek script is not loaded, then get_bool gives a fatal error. So there is no longer a dependency on the other analyzer, but on the zeek script within the same analyzer.
I therefore used johanna’s solution in the post How to push status information from a spicy parser to an cpp parser? and added a very simple C++ function to the spicy parser that queries the analyzer_mgr directly. Now there is no dependency on a zeek scripts anymore.
Nevertheless, your suggestion has helped me a lot. Thanks for that!