It would be fantastic if you could allow Jira to push through updates on fix version to Aha!. I was discussing this briefly with your support team and they mentioned that the goal is that Project Managers are managing releases through Aha!. However as I mentioned to here that sometimes things a little faster to change in Jira so it can be easier to do it there. Another thing is that in our company to work fast we enable our team to create their own tickets when they are known technical tasks that need to get done in a release that may not have to go through the official process. We want to track these in our fixVersion - but because they come from the devs - when a fixVersion is added or changed by them we don't see the changes in Aha.
Its possibly the biggest limiting factor for myself and my team and how we like to work. I totally understand that not all companies work this way but it would be really great if you could consider this.