1.Is there any architectural information about the Genesys Bot Connector design?
The Bot Connector Customer API spec is here and includes a diagram and explanations.
2.Do I always need an intermediary JSON translation app to work with third-party bots and Genesys Bot Connector?
You need to comply with what is sent over the postUterrance webhook, and what is expected in return - which both are JSON based schema.
The JSON schema of what is sent to your server application over the postUtterance webhook is defined in the postUtterance send schema.
And Genesys Cloud expects a response which comply with the postUtterance response schema.