Power ratings for micro JST
No, your understanding is not correct and you can't increase the current at lower voltages.

The current rating is the maximum current that can pass through the connector without damaging the connector. This would be limited by the inherent current-carrying ability of the conducting parts of the connector. The voltage rating indicates the maximum voltage difference that can safely appear continuously between two conductors in the connector...a higher voltage would require more spacing and/or better insulation between conductors. So, these limits are not telling you how much power can be dissipated within the connector.

You must satisfy both limits all the time.