How many voting irregularities do we tolerate? Would the community managers consider giving such users a permanent suspension?
There's a bit of a misconception about suspensions that I'd like to clear up.
CMs can't do multi-year, single-site suspensions. We have the same limitations as mods in that regard. We can only issue multi-year suspensions network-wide and, in general, unless a user is rampaging across the network causing problems we're not going to network suspend them... well, OK... maybe not rampaging - but the point is, we don't give network wide suspensions for users who are generally only causing issues on a single site.
Also, permanent suspensions (or very long term ones) don't really... serve a huge purpose other than to push a user to more sock puppets. If you get a 30-day or even a one-year suspension and you have a bunch of reputation, it's doable to wait it out and come back next year. If you have a ten-year suspension, you might as well forget the account and start over from scratch - we don't suggest this as if you repeat the same behaviors, you can be easy to catch, but it can be possible for some.
As to the suspension duration - that's up to the moderators on the site. Remember, they have tons more info than you do and they often get additional information or guidance from the CMs to help them make their decisions. If a mod feels like a two-week suspension is the appropriate response, even after two full year suspensions... that's OK.
The slug on a user's profile when they're suspended is a very broad statement that doesn't really tell you enough information to make any assumptions. We do generally recommend a standard escalation of suspensions that looks like:
warning -> 7-day -> 30-day -> 365 day
However, moderators are free to choose any number of days between 1 and 365 at any time based on the severity of the situation and we generally trust them to make good ones. Users can always contest the duration of their own suspensions by using the contact form. Another user could theoretically request review of a user's suspension duration if they wish but doing so would likely only result in a generic, "we'll look into it" response since we can not give any additional information.
In general, unless you know exactly what happened in the past and what happened to cause the current suspension and feel absolutely that a moderator or the moderator team is not judging the situation correctly, I would recommend against any such contact. As I've said, moderators and CMs have a lot more info and base decisions on that information and their experience. Clearly, the moderators had little issue granting year-long suspensions in the past so I'd trust them to have made an intentional decision in this case.