Complex PTSD and EUPD are distinct diagnoses. There is some overlap though, in that both are rooted in trauma. In Complex PTSD the ‘trauma’ symptoms would be seen to predominate (flashbacks, avoidance, hyper vigilance, anxiety), whereas in EUPD there is emotional instability along with issues in relation to sense of self and interpersonal relationships (stable sense of identity, self-direction, intimacy, empathy) along with the emotional instability component. As said, there is overlap, the same patient may be given both diagnoses either together or at different points. Psychiatric diagnoses are notoriously subjective anyway, their main point is to guide management and give the person a way of trying to understand and manage their difficulties.
There is an issue with EUPD being diagnosed as BPAD, not so much the other way round.
Unfortunately yes, the condition is stigmatised, 2 well known studies have shown this, the famous one by Appleby in 1990s (famously dubbed PD ‘the patients psychiatrists dislike’) and was replicated in around 2017 showing the same.
I work in mental health. Most people I would say are actually empathetic or try to be. Obviously not everyone though. The fact that patients who present with a lot of risk and are difficult to manage lead to a great deal of anxiety among staff can affect attitudes, hence importance of effective supervision/ reflective practice to support staff and by extension patients.
There is lots of evidence that PD is not as stable a diagnosis as once assumed, it tends to improve with time in a lot of people, with effective management and if people are able to develop effective coping strategies and manage stressors.