⚖️ Per definisi berikut:

https://dictionary.thelaw.com/cross-complaint/
CROSS-COMPLAINT
TheLaw.com Law Dictionary & Black's Law Dictionary 2nd Ed.
Also called a cross-claim, this is the filing of a legal claim against the original plaintiff, a co-defendant or another party that is not yet a party to the lawsuit and where the underlying facts are the same as the original lawsuit.

Boleh dikatakan ini suatu gugatan ke segala arah oleh tergugat, selama pokok masalahnya sama.

👩🏽‍⚖️ Namun, dari sebuah situs pengadilan kepailitan AS (perusahaan di atas, BROOKS BROTHERS GROUP, INC. berdomisili hukum di sini, IMO), diperoleh definisi berikut:

http://www.mssb.uscourts.gov/RoboHelp/ECF_Docketing_Guide/Ad...
Counterclaim A counterclaim is a claim by a defendant against a plaintiff.
Cross-Claim A cross-claim is a claim by one party against a co-party (e.g., a defendant claiming against another defendant, or a plaintiff claiming against another plaintiff, arising out of the original complaint.)
Third-Party Complaint A third-party complaint is a claim asserted by a defendant ("Third-party Plaintiff") against a nonparty....

Nah, dari definisi pengadilan itu, boleh disimpulkan:

☑️ counter-claim: gugatan balik atau gugatan balas (atau lebih populer gugatan rekonvensi per pengadilan Indonesia)
☑️ cross-claim (istilah lain cross-complaint): gugatan sama pihak (entah sesama tergugat atau sesama penggugat, dan ini mungkin belum dikenal di pengadilan Indonesia)
☑️ third-party complaint: gugatan pihak ketiga atau gugatan luar pihak. Saya kurang yakin bahwa ini dikenal dalam sistem pengadilan Indonesia. Ada yang namanya gugatan perlawanan, namun itu hanya dapat dilakukan setelah ada putusan, bukan selama proses acara persidangan. (Lihat: https://www.hukumonline.com/klinik/detail/ulasan/lt5805adbab... )

Untuk pelakunya (complainant), kita tinggal ganti imbuhan: penggugat sama pihak (yang lain: penggugat balik, penggugat luar pihak, dst.)