When the Host receives a "Startup Sync Request" from the Module, should the Host always complete the Startup Synchronization flow?
Yes, every time the Host receives a "Startup Sync Request" from the Module, it should go into the host startup configuration flow. The only two cases in which the Module will send a "Startup Sync Request" are when it has powered up after a hard or soft reset or when it has received a Host Startup Ready" from the Host.
Note that the Module will also send its Configuration State with the "Startup Sync Request" which will tell you how much configuration you need to do from the Host side. For more information, please see the Startup Synchronization section of our Serial Protocol documentation.
You can also find an example of the startup sync state machine in our Simple Java Host.