For use with data, there is no requirement that a port be labeled for charging so long as the charge is within the normal USB current limits. In that case both charge and data are simply available as a generic USB device power consumption (using a host to provide power has nothing to distinguish whether the power is being used by the device directly, or to the battery charge). Additional circuitry may be present for detection and charge versus data modes if the port is intended to switch between dedicated charger and normal USB use.
In your case where ports are advertised as “fast charging”, I can’t say whether these behave as normal data ports. The point about being unpowered versus powered is mainly that an unpowered HUB has limits based on a limited amount of power from the upstream port being split up among one or more downstream ports…if more than one device is attached to the HUB you have to worry about cumulative current draw of all ports when unpowered. When the HUB is powered, you no longer have to care about the host’s power being split among each port…in that case each port is rated to a higher current rating and all ports can draw their max at once. Having two cameras, where each might pull significant current automatically means you are better off with an externally powered HUB.
If the “fast charge” ports do not also work as regular data, then there is a problem. The fact that your HUB is externally powered is good, so long as those fast charge ports don’t eliminate normal USB function.