The buttons issue has been fixed (well, worked around while attempting to optimize something else, but I'll take it ;p) in KOReader, FWIW.
(The Libra 1 *also* had a weird EPDC issue (
details), although it was less fatal, and more easily worked around).
Both the Libra 2 and the Sage have since seen a newer hardware revision with a different PMIC that may (or may not, reports are inconclusive; and the switch might just be a supply chain issue) alleviate some of their respective issues.
AFAIK, the Libra 2 *also* exhibits worse power efficiency than it ought to for an i.MX6-based device, so it's not entirely rosy... That's in addition to its ridonkulous (and fatal) EPDC issues.
(I wouldn't touch a Libra 2 with a 10-foot pole myself, while I'm happily running a Sage as my daily driver).