Nope not broken at all. Sorry but I was wrong... no call of Convoy Sighted. Just the call of Ship Sighted, which can be the first ship sighted in a convoy.
But.... Task Force Sighted does come up for 2 armed Troop ships, not Merchants. If that was the case stated perviously, a convoy of Merchants and Tankers would be called a Task Force if all were armed. And that doesn't happen in my SH5. No, I'm not running the 'Speech fixes and additions (english version) V1.0' mod. My understanding is it's for CSP Magui 3.0... which I'm not using.
Just had this happen in British Coastal Waters.