Welcome to BPDFamily, happy to meet you, sorry you're here...
I think it sounds like great news that she's been taken into an inpatient centre; from what I've heard from others, the hardest part is that first entry because often they'll resist it with the most furor. But having gotten your foot in the door here, so to speak, even if this particular intervention ends up not being entirely successful...she'll be hopefully more likely to seek out help in the future.
The "good news" I can offer from personal observation is that while "normal" doctors and nurses are often very UNhelpful to people with Borderline Personalities because they just glomp "psych cases" together in their head - the medical staff at inpatient psychiatric wellness centres are actually REALLY good at responding to Borderline Personalities because they understand the distinction between how you respond to a normal person making a suicide threat versus a BPD, how to react to violence from a BPD rather than from a normal person, etc. The pwBPD I saw the most in that environment had some bruises from staff members that she crowed about endlessly, how she was going to sue them for tackling her, etc - but ultimately they seemed to be doing her some good...and it seemed like they might be the first people in a long time who helped her learn how to control herself. I didn't follow-up with her long-term after discharge so I'm not sure about the lasting effects, but yeah - I'd say the medical staff at an inpatient facility like that are really much better than general hospital/medical/therapy staff.
I've spent a decade reminding people (including a very entertaining week this past week) that "No, BPD is not Bipolar (nor does it mean they're almost-Bipolar) and please do not respond to BPDs or judge them the way you do with Bipolars"...but it's how even doctors outside of specialists tend to view it. So getting her in a place where even the janitorial staff have an understanding of the "Borderline" patients as distinct from the OCD, p. schizos, etc, is worth its weight in gold.