If the bot user is kicked from IRC, it should notify the mapped Matrix rooms about it

[kfatehi]

From what I understand, the appservice bot (the one that sits in IRC, if enabled in the config.yaml) is really only useful for when there are no matrix-side users in the room, to hear the messages and keep them synced on the homeserver.

When the bot is disabled, it will use the matrix-users for that.

When the bot is enabled, it actually is single-point-of-failure with a non-obvious failure state, simply by being kicked. And does not self-heal (retry join).

[kegsay]

Your understanding is correct.

When in bot-only mode, the bot does not attempt to re-join after being kicked by design, to avoid pissing off IRC users with obnoxious auto-rejoining bots. It could send a message to the corresponding Matrix room however.