Yes, an 85mm on a FF35 camera would get you something like a 50mm on a 35mm movie camera. I'm using a 1.7X crop factor to calculate the difference in view between the 21mm width of standard 35mm cine and the 36mm width of FF35.
Though your aspect ratio affects your perception of how "wide" the shot is. On the old 4x3 format of movies before the mid-1950's, a 50mm "felt" wider in view than it did later when movies cropped the height to 1.85, even though the horizontal view stayed the same, so you had to switch to a 40mm or shorter to keep the same "feeling" as the 50mm got you in Academy or Silent Era photography.
And if you will be cropping to 2.40 : 1, this is even more true.
Anamorphics are more complicated -- they are like using a spherical lens with a 2X wide-angle adaptor except that the image only gets wider in view horizontally. So a 40mm anamorphic lens sees horizontally like a 20mm spherical lens. So if you think of it in those terms, if a lot of "Solaris" was shot on a 40mm anamorphic lens for its wider-angle shots, you'd have to use something like a 35mm on a FF35 camera (20mm x 1.7 = 34mm). But I don't know what anamorphic lenses were used on "Solaris" -- the interior clip feels like a 50mm anamorphic was used.
Yes, a lot of "In the Mood for Love" looks like a 50mm or 85mm or 100mm lens was used in small spaces, the camera backed up past doorways and windows to look in with a longer lens. But there are wider-angle shots in the movie too. The trouble with committing to just getting one lens is that it might not be wide or long enough for some of your spaces. Wong Kar Wai made it part of the style to put the camera where it could fit in these small apartments, even if it meant looking through doorframes that are blocking part of the frame, but your locations might not afford you those angles.