Q, do those definitions in global configuration, defined as routing-options static route
Interact with Zones or Security Policies?
Or is it only for the basic functionality related to the Firewall as a device (I mean, for the syslog/NTP/… accessibility)
The routing helps to determine which zone is involved with a flow which then determines which security policy will apply.
When a packet arrives, the ingress interface belongs to a zone, this is the from-zone for the policy check.
A route lookup occurs for the destination address, this determines then the egress interface for the traffic and the zone assigned to this interface is the to-zone in the policy check.