We start using your platform and faced a few issues:
1) If we update a field with an API it is not triggering updates in journeys
2) According to your documentation, we need "trigger_key"
to trigger the journey with API, but when we get the info about journeys there is no trigger_key field - only Journey_key and with it it doesn't work.
3) Journey through your system couldn't go for one lead more than 1 time.
The best way if we can trigger the journey with our system every time we update the contact.
But it aslo would be ok if your system could notice a change of the field with API and push it into journey
Also, want to notice, journey is set up on filed update