IMO, you don't need to stress too much about the other clefs at this level. A professional player can sightread all clefs easily, but for the student you only see the other clefs in solo works and occasionally short sections in some orchestra parts. In both cases if you are shedding the stuff like crazy in the practice room like you should be, you will memorize the notes soon enough, so not being able to sightread them fluidly isn't something to worry about. If the clefs are such a mystery that you are having trouble even getting started learning the parts, then you should book some extra time with your teacher. I was a terrible sightreader as a teen. At some point the problem just went away. I don't remember when.