As another Bahá’í, I’m gonna offer a similar perspective to the OP. Of course, it’s colored by my own understanding and experiences.
1. As for people of different religions coming together, I’m optimistic on that front. Young adults in my generation are understanding that different religions offer valuable insights into how to live life, not necessarily that they teach exactly the same things. Anyway, the differences in religion are not necessary to argue over. Doing so is nothing else but problematic. Open-mindedness is the main thing. The goal of, really, any religion is to show us the nature of Ultimate Reality, human nature, our relationship to life and the universe, the meaning of life, and to cultivate practices reflecting these. Hence, you have, for instance, Christians – many of whom are notorious for denying that there even is wisdom in other religions – practicing things like Buddhist meditation and astrology, and engaging in Hatha Yoga. They see that there are keys of insight in other religions that can unlock doors of understanding in their own religion. Followers of every religion would do well to adopt this mindset. It’s the mindsets of people, not the variety of religious teachings, that separate.
2. With this said, I do not believe that it is necessary for people to become Bahá’ís in order to do this. For me, it’s better if individuals travel to the heart of each religion, starting with their own, and engage with each each one, insofar as their own minds permit them to. Conversion to another religion is not necessary.
3. Concerning the notion that Bahá’í conceptions about X religion or Y religion indicate that they privilege one particular sect of said religion over another, this is quite confusing to me. While the Bahá’í Faith originated from a specific cultural milieu (that of Persian Shia Islam) and had engaged with a broader backdrop of Judaism, Christianity, Sunni Islam, Zoroastrianism, and (via literary influences among the nobility at the time) Vaishnava Hinduism, this doesn’t necessarily imply that Bahá’u’lláh saw other sects and religions as invalid. His understanding, and resultingly ours, of the religions He engaged with, again while colored by His cultural and individual background, was non-sectarian.