Sad. The have the time to, at least attempt, to be funny. They have time to add new resorts. They don't have time to correct serious errors. Years ago I exchanged messages with the OLP people. They said they were going to make the changes. They didn't. A year or so after that a couple of posters on DIS did the same thing.
DHS, not EPCOT, is a transfer point from any resort to an EPCOT resort. Using EPCOT requires a long walk through EPCOT and requires park admission. Not an issue if you have an AP or hopper (and have a reason to walk through EPCOT). Last time I checked they were still using EPCOT as a transfer point.
I've to the conclusion the people behind the OLP transportation wizard are sadistic people who enjoy giving out wrong directions, presented in a way that make them look accurate.
They fooled Shelly F - Ohio.
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And for the longest time they didn't have the Poly as a transportation hub on its own. For instance, you used to be able to put Poly at the start and EPCOT at the end, and it would have you ride the resort monorail all the way around to the TTC, and then transfer to the EPCOT monorail. Just a little time spent at the Poly tells you that the TTC is literally steps away, which of course saves tons of time versus taking the monorail all the way around. It appears that they finally fixed that problem, but it took them YEARS to do so.
Because the transportation wizard on that site is so flawed, I have problems trusting any other information that site tries to impart. For all I know the rest of their info could be 100% correct, but the transportation wizard is a deal breaker for me.
OP, the quickest "Disney" way to get from Poly to HDDR is, like others said, to take the monorail or boat from Poly to MK, and then the boat from MK to FW. A cab would of course be much faster, since the resorts are pretty close together as a crow flies.
For the return trip, if HDDR ends after MK has closed for the night, they might have buses going to each resort. Otherwise, I'd take the boat from FW back to MK, and then get on the boat (and not the monorail) at MK going back to the Poly. At the end of the day, the boats going to Poly/GF are typically faster than the resort monorail, and require fewer stops.