Have any HCSSs (supermassive black holes with a tight bunch of gravitationally bound stars) ever been detected?

Question

This article from sciencealert states:

Astronomers think these two galactic cores could merge into one larger black hole, sending huge gravitational waves rippling out across spacetime. But if there's any asymmetry in the galactic merger, the newly forged black hole could be punted clean out of the galaxy and sent zooming across the Universe by gravitational wave recoil, taking a swarm of stars with it. Such runaway objects, theorised in the late noughties, are called hypercompact stellar systems (HCSSs) - a supermassive black hole with a tight bunch of gravitationally bound stars, careening away into the cosmos.

This article was written in 2020; now is the end of 2021. Have any HCSSs (supermassive black holes with a tight bunch of gravitationally bound stars) been detected since then?

What projects are currently actively searching for HCSSs?

Answer 1

The referred by me article was of 2020. Now is the end of 2021... Were any HCSSs - (supermassive black holes with a tight bunch of gravitationally bound stars) have been detected since then by now?

No, not yet.

What projects are currently actively searching for HCSSs?

This recent study, A Search for Wandering Black Holes in the Milky Way with Gaia and DECaLS, for such systems near the Milky Way used data from Gaia and DECaLs. They expected to see "~100 wandering intermediate-mass black holes if every infalling satellite hosts a black hole," but no such black holes were found in their search.

For future outlook, this recent study, Hypercompact stellar clusters: morphological renditions and spectrophotometric models, explores prospects for observing these systems with "Pan-STARRS and in forthcoming Euclid images."