It's always tricky to get system synergy. i built my setup specifically for my Susvara, but even then there are times my system did sound bright with my Susvara (even with my XP-12/XA25). This happened after I upgraded from my Spring KTE to my May KTE. I was using a Wireworld Platinum Eclipse interconnect between DAC and pre which was a revelation with the Spring KTE, but was too bright for my taste with the more neutral May (I ended up solving this by swapping in a Norne S4 interconnect, also silver). So it's hard to say where her issue might be specifically.
She likes Empy and 1266, but finds Susvara bright. From everything I've read, I don't think I would like 1266 because of it's FR in the upper ranges. From what others have said about Empy, it sounds veiled compared to Susvara; if she's not valuing the detail (and possibly microdynamics, timbre) from the Susvara, then maybe it's just not a good fit for her preferences. There is no perfect headphone that works for everyone. We each have our own preferences and hear in our own way, so it may just come down to that.
I'd also add, that I don't use my Susvara for everything I listen to. I prefer it for vocal, acoustic, intstrumental, but will use my EQ'd LCD-4 for more bass dependent genres (esp. if they are also bright crappy recordings). I don't recall her mentioning what kind of music she listens to, so that might also be a factor (e.g. if you're looking for bass slam, then you probably won't pick a Susvara over a 1266).