POTENTIAL CONFLICT WITH OPPOSITE DIRECTION TFC IN THE TFC PATTERN.

Narrative

WE WERE CLRED BY COCO TWR APCH TO EXECUTE THE ILS/LOC RWY 7 CIRCLE TO RWY 25; BECAUSE THE WIND WAS GREATER THAN A 10 KT TAILWIND ON RWY 7. ON L DOWNWIND AT 1000 FT OF THE CIRCLE WE SAW A SINGLE ENG PROP LOWERING AT APPROX 1:30 TO 2 O'CLOCK POS IN A TURN AWAY FROM US; THERE WAS NO NEED FOR EVASIVE ACTION AND THE ACFT RPTEDLY HAD US IN SIGHT ACCORDING TO THE TWR OPERATOR. WE CONTINUED A NORMAL APCH AND LNDG. CTLR WAS TALKING TO THE SINGLE ENG PLT IN SPANISH AND SAID THAT HE HAD TOLD HIM WHERE WE WERE AND THAT HE (SINGLE ENG) HAD US IN SIGHT. THIS WHOLE SCENARIO COULD HAVE BEEN MINIMIZED IF THE TWR CTLR WOULD HAVE BEEN SPEAKING ENGLISH; BECAUSE WE WOULD HAVE BEEN AWARE OF HIS POS ALSO. ONLY VISUAL RESTRS WERE SLIGHT HAZE/SMOKE IN THE AREA AT THAT ALT. SUPPLEMENTAL INFO FROM ACN 271976: DURING L DOWNWIND AT MDA OF 4020 OR 1000 AGL. THERE WAS A CHEROKEE 140 FLYING IN THE OPPOSITE DIRECTION AT THE SAME ALT. THE TWR KNEW THE POS OF THIS CHEROKEE AND THE DIRECTION OF HIS FLT; BUT NEVER ADVISED US OF THIS TFC. THE TWR NEEDED TO ADVISE US (B-757) OF THE POS OF THIS CHEROKEE SO WE COULD LOOK FOR HIM. THE TWR TOLD THE CHEROKEE WE WERE INBOUND.