Obviously it has a (well deserved) reputation for being impossible to complete and glitched, but the potential for it to be a fun STF is there. Are there any plans to fix it? If so, when? Season 7? Season 8?

I doubt it will be touched again.

The problem, as I see it, is that Cryptic gives too much freedom to it's developers on 'how' they go about creating missions (as well as other things). They only seem to care about whether something gets done or not. Because of this, when the developers who originally made things leave the company, the knowledge about original design intent and why certain things happen in the code or mission mechanics is lost. Nothing seems to be documented sufficiently. So it becomes more of a challenge for the next developer to get to grips with what made the mission tick, in order to fix an issue and return the mission to it's originally designed intent. And those who do may similarly be allowed to make changes without documenting them sufficiently (i.e. so that anyone looking at those changes in 5 years time can grasp what they are doing and why).

Until this type of laissez faire developing is addressed, I don't think we'll see resolutions to longstanding issues in older content, simply because it comes at too great a cost in developer time that could otherwise be better spent on new content, which pays the bills.