My only 2c is to debug/test without using Siri. Consider Siri as an overlay/front-end to HomeKit that adds extra confusion (Siri has it's own naming conflicts, sometimes responds differently when you issue the exact same command, works differently without warning as Apple updates the back-end AI, etc.)
If things work in HomeKit, then you can separately deal with the challenges of trying to control them with voice via Siri w/o wondering if the underlying device or bridge is not working properly.
Do your testing/working with Apple's HomeKit app, but also be sure and use the 3rd party "Home" app by Hochgatterer @brutella (well worth the money) - that app exposes more of the underlying HomeKit structure and provides more options for configuring HomeKit automations.
Sure, you're using Indigo and HomeBridge to keep using the more advanced automations and capability in Indigo instead, but there are times when you will want to see a little more "under the hood" of HomeKit and the "Home" app will do that.
For me, I use HomeKit as a GeoFence input to Indigo. I have an Indigo variable mapped to an Indigo virtual device which is then exposed to HomeKit and have configured a HomeKit automation to update the virtual device (on or off) when I enter or leave my home. This gives me an easy way to write all kinds of conditional stuff in Indigo based on GeoFence status. Much better than the Wi-Fi hacks or using IFTTT/Stringify Geofence-to-email glue.