Asking for clarification
From the JACC:
Yesterday afternoon, Bluefin-21 completed its last mission searching the remaining areas in the vicinity of the acoustic signals detected in early April by the Towed Pinger Locator deployed from ADV Ocean Shield, within its depth operating limits.
You are quite right, it could be understood as meaning that Bluefin only searched areas which were within its operating depth BUT if you read on to the 4th paragraph, it states:
The Australian Transport Safety Bureau (ATSB) has advised that the search in the vicinity of the acoustic detections can now be considered complete and in its professional judgement, the area can now be discounted as the final resting place of MH370.
The above leaves no doubt that Bluefin completed the search and did so within its operating limitations.
Well, that's how I understand it but could be corrected.