Yup, each remote can control up to 30 bulbs as one group. It always controls all the bulbs paired to it. It does work with non-LL lights like GE Links. They can create their own zigbee network by “stealing” bulbs, but if you pair it to your ST hub/network first, it can control bulbs while on the ST network.
ST does not see the button presses because it only sends group commands, which are not supported by ST’s implementation of zigbee at this time. It is on the list for future improvements. There’s an Alpha version of an official devicetype, but since ST can’t see the group commands, it really just gives the device a button icon.