I heard a transmission on 6577, with the controller saying 5550 was the backup at the moment. Neither was listed on the Collins site at that time.
They seem to be slow to update the site at times. This morning the Collins site is only showing 8846 and 13297 active in the WAT* area. While 8846 and 13297 are active so is 8825 that's not listed. Same as yesterday when 8825 was active and the Collins site did show it, but it's not listed today for some reason.
The area descriptions don't make a lot of sense either. In reality the "Gulf of Mexico / S. America" frequencies correspond with the southern area of the WAT (south of Bermuda and generally south of M328). This area doesn't include the Gulf of Mexico or S. America.
The "Caribbean / N. Atlantic" and "Northeast U.S." frequencies correspond to the same northern area of the WAT (north of Bermuda and generally north of M328). So I'm not sure why they have 2 different listings.
The "Eastern Atlantic" area is accurate (east of 60W) and the frequencies listed are usually corrrect. The NAT-E area seems to have been removed with some of those frequencies now being used in the WAT area (like 8825 and 11309). With the NAT-A frequencies now covering all the Eastern Atlantic. This happend a few years ago but I've never seen anything updated in any docs. or charts so maybe not an official change.
*WAT = West Atlantic (west of 60W, formally known as WATRS aka CAR-A/B).