To get to Disney Springs, you have to use the pedestrian bridge. There are stairs and elevators on both sides of Hotel Plaza Blvd. So, you don't have to be on the one side to cross the street.
On a previous stay, I timed the walk to the DoubleTree Suites. The time from the edge of the Marketplace section to the front door of the hotel was 14 minutes. It's a pleasant walk on a divided, landscape sidewalk. Image courtesy of Google Maps:
I'm fairly nocturnal. I've walked alone from the DoubleTree Suites to the Hilton Lake Buena Vista at 3am (to go to their 24-hour market) and never felt even remotely unsafe. I've walked alone from the DoubleTree Suites to the 24-hour Perkins in the Crossroads Shopping area in the middle of the night without issue. As evidenced by my username, I'm a man. But, if you're walking back from Disney Springs after dark but before midnight, I can't imagine you'd feel any concern...particularly if you're not alone.
As for the Hilton, keep in mind there are two different Hilton Hotels across the street from each other next to Disney Springs. The Hilton Buena Vista Palace is completing a massive, multi-million dollar renovation.
The Hilton Lake Buena Vista is a hotel that in my opinion is in dire need of a renovation. I've stayed there for 40+ night over the past few years and never had a problem-free stay. As a result, I only stay there if the total price including resort fee is under $100. It's not worth more than that.