Well, it's not the Jones Act, firstly. It's the Passenger Vessel Services Act. A closed loop cruise from a US port only requires a foreign port stop (near OR far). An open jaw cruise from one US port to a DIFFERENT US port requires a DISTANT foreign port stop.
The issue is that a foreign flagged ship cannot transport a passenger from one US port to a DIFFERENT US port without a stop in a distant foreign port.
The San Diego/Ft Lauderdale most likely has such a port.
Booking Ft Lauderdale/Montreal B2B with Montreal/Boston does not have a distant foreign port.
That said, San Diego to Boston (the cruise the OP was booked on) does satisfy the PVSA. I don't understand why they thought it didn't. Only thing I can see is that HAL has issues when such B2B cruises are booked under separate reservations and the computer flagged the Ft Lauderdale/Montreal and Montreal/Boston legs as violating the PVSA.
I had a little bit of progress - when I click on the link to go to the HAL website, that page opens for me. But as soon as I click on any link (My Account; Manage My Booking; Site Map) I get the greyed out screen with the spinning circle.
GENERALLY, they release the dates about 18 months out. Historically (prior to COVID) this is what happened:
"Winter": first cruise in the new year up to April/May (not including spring Panama Canal and Transatlantic) – sometime between late September to early November
"Summer": cruises from about May to August/September (not including fall Panama Canal and Transatlantic) – mid February to early April.
"Fall": September until the end of the year (ending with the last cruise starting in the old year) – generally around May.
So, I wouldn't expect fall cruises to show up before late spring.
I know they usually just stash the stuff from the minifridge in the room, but I like to have the steward empty it. Just so I know (and they know) that the stuff in there is mine and they don't "replenish" the stock with minifridge items because they think we've used some (meaning we get charged for it).
Not for me. When I go to the website, for a second it looks good, then it defaults to the greyed out screen with the spinning wheel. The "log in" isn't on that page for me. It is there when I'm on the site incognito.
Generally speaking, I'm in the "longer is better" camp. So whichever cruise is longer would (most likely) win.
2nd consideration is ports of call - if there are ports I want to visit on one but not the other that would win.
3rd consideration would be cost.
We only take passports ashore if it's required to have them on us while there.
Otherwise, they stay onboard, in the safe.
Ship's card and photo ID works.
It depends on the turnaround port country's laws. Generally, if the turn around port is in the US, the ship has to be cleared before new boarding can begin. Other countries, it may or may not be required.
Now I wish I could check my booking without jumping through hoops (website is a mess for me, doesn't connect, can't log in, yuck). I believe we have HIA with Elite beverage package included.