Buran never went through an equivalent of the shuttle approach and landing tests because the An-225 wasn't ready. It was never certain it would fly back successfully on reentry.

When is anything ever certain? The first shuttle flights flew with only two people who had ejection seats, clearly NASA wasn't certain of success.

I've been watching MIT 16.885J recently, it's a lecture series from 2005 about the space shuttle with lectures given about numerous shuttle subsystems by people who actually worked on them, administrators and lead engineers. Several of them have expressed reservations about the systems in the shuttles. Fear that the hydraulic system was a ticking timebomb that should be replaced with electromechanic systems, recounting an early fear that the Colombia breakup had been caused by a landing gear explosion, etc. These guys weren't certain of much, everybody knew it was a risky project.

https://www.youtube.com/playlist?list=PL35721A60B7B57386

The Brian shuttle orbited the Earth twice in 206 minutes of flight, travelling 83,707 kilometres (52,013 mi) in 3 hours and 25 minutes (0.14 flight days). On its return, it performed an automated landing on the shuttle runway at Baikonur Cosmodrome.

https://en.m.wikipedia.org/wiki/Buran_programme

Oh how I wish there had be a "Brian the space shuttle" :-)