Not a bad idea but realize that any useful discussions of this nature will be deleted either by the op themselves to preserve a film from takedown notices, or by reddit mods because these types of discussions are not allowed.
The ones you're looking for aren't hard to find anyway, at least in the US. HBO controls En El Septimo Dia so you can view it either through an HBO subscription, HBO free trial directly through HBO, or through an HBO trial through Amazon Prime. (If you already used up your HBO free trial, it's possible to get two free trials to services like HBO, Showtime etc without using two different credit cards, if one of the trials is via Prime. Also you can do it during a free trial of Prime, so you don't need to pay Amazon anything either. Hulu also offers some of these options, but maybe not with HBO, idk.)
Mutual Appreciation can't be that hard to find on torrents or RARs. Check slsk too. It's an American film by a well known director, released in the peak era of torrents. It appeared on Mubi earlier this year too.
For me, the biggest rarity is Lav Diaz's 2001 breakthrough film Batang West Side (West Side Kid). If I spent half a day I'm pretty sure I could locate it (one reason I have only intermittently tried is that I usually lack disk space for dealing with zipped files of a 4-6 hour movie) but I'm not sure if there is a good set of subs.
Gavazhna (The Deer), a very important 1970s pre-Revolutionary Iranian new wave film, is another one that's out there widely, but with an imperfect sub situation (two different cuts of the movie exist, a censored and uncensored one, and subs I found are matched to the wrong one).
Art films/video art is the worst. Even if you're looking for an extremely famous and hyped "one channel installation" (what us cinephile plebs call "a film") the rights situation is so heavily locked down that you'll almost never see these things online until decades after they premiere in museums. Two- and more-channel installations are designed for a particular 3D gallery space and can't be viewed ideally on a single screen (although split screen can get across a general idea), so it's understandable why no one is usually offering those either legally or illegally online, but single-channel videos are only absent for capitalistic reasons, because the art market demands the artificial creation of scarcity, even for multimedia works that resemble the type of content ideally suited to Youtube.
It's not a matter of the artist making a living. It would be great if you could buy or rent these things, even if you couldn't get them free, but allowing even an individual purchase of these works would reduce their million dollar values in the art market. Rich guys would be less interested in buying them if the public had any means to see them.
Considering how many filmmakers who could once rely on a theatrical art film circuit are now having to rely on museums (everyone from Tsai Ming-liang to Arthur Jafa) it's pretty disgusting how the public is limited from ever seeing their work. The art world establishment is even more corrupt and greedy than Hollywood.