As I knew they won't promise a return offer for interns. But I can tell it is not easy for them to hire quality fresh graduates so even if it is not a direct return offer, those interviews should be just walking through some processes as far as you did great during your internship. Trust me, in this world only a very limited number of companies would offer direct return offers, majority of the employers will just offer fast tracks but it is quite exclusive already.

As a career start, I would just rank Computershare a fair grade in my personal perspective as the industry itself is quite unique. For sure it is the leading player in that but yea it really depends on which departments you are working for when we examine its value to your mid or even late-career. I saw a few examples some can develop a finance career in banking / financial institutions while more others are just jumping around different companies and industries in their job domain (eg HR / Marketing). I wouldn't say it is a really prominent career start but may be a good exp as an intern I guess.