Hi, Carissa, each workshop maintains separate credit accounts (so that people critique in the areas that they want to be critiqued), though there is sharing of excess credits above the 75% minimum in another workshop. For example, if you had a 200% ratio in the SF workshop, some of that credit would carry over to manga -- based on a formula listed in the www.critique.org/c/extracredits.ht
page -- but the idea really is for people to critique in the areas they create. Doing critiques really helps improve one's craft, so it shouldn't be viewed as some unrelated chore; it's very related and useful.
So, there is one piece up for critique in the manga workshop, which you should definitely critique.
And I'm not sure what you mean by not being able to get on the queue -- anyone can submit anything into the queue at any time, regardless of ratio. Just send it in. It will go on the list. What matters is what your participation ratio is the day it's scheduled to go out
. You have until that day (or the day before) to get your ratio up to snuff.
Hope that helps clarify.