Is the Anker X1-H-T X1-H12K-T compatible with the Anker DTSU666 3ph CT?

Yes — listed by the manufacturer.

The manufacturer's published pairing data lists these together.

Manufacturer's compatibility listListed together in the manufacturer's published pairing data. A cited document reference is being added as datasheets are processed.

Pairing details

CT specification
cts: 3x CTs (1 per phase) with DTSU666; 1x CT with DDSU666 · note: DDSU666 for single-phase grid; DTSU666 for three-phase; SDM230 for AC-coupled · type: Split-core · cableLength: 1m · maxExtension: Unconfirmed — check Anker installation manual

Both products

Design a system with this pair