I agree with 59Impala and others. At least in the US, "Junior Suite" almost always means a larger single room with some sort of sitting/lounging area but rarely (if ever) comes with a door between the rooms.

I think that as long as one of the true suites was available for your entire booking period (Park Suite King/Twin) the hotel should have proactively upgraded you to it. And if they don't, you should feel free to escalate saying the Terms and Conditions will give a globalist an upgrade to the best room available including standard suites.
You are NOT guaranteed an upgrade to a premium suite (so if Park Executive is the only upgrade available they do not have to give it to you).

All that being said - my general globalist experience is that half the time they'll give you the upgrade if available proactively. Half the time if you say "Park Suite Twin looks like it's available for my stay, can you do a Globalist upgrade to that?" then they'll do so.
I've only had a handful of times where it looked like the room was available and they weren't willing to upgrade to it (and in those cases they had already given me some sort of an upgrade).