I believe that Kafei is Link's Terminian counterpart, but not just off of appearances.
First, I'll explain with their situations. In the previous game, Ocarina of Time, Link started as a child, and after pulling the Master Sword out of the Pedestal of Time, he was sealed for 7 years and became an adult. Kafei on the other hand, encounters the Skull Kid, through some unseen event, and is transformed from a man to a kid. The two situations are opposite, but they're still very much alike.
Another thing I would like to bring up is the Ocarina of Time and the Pendant of Memories. In the beginning of Majora's Mask, Link loses the Ocarina of Time. When he gets it back, we find out that the Ocarina of Time was given to him by Princess Zelda. Kafei has the Pendant of Memories and gives it to Link so he can deliver it to Anju. Link obtains an item from someone precious to him; Kafei gives an item to someone precious to him.
As for the Anju and Saria bit, I don't agree. Also, I'd like to bring up that just because Anju is similar to the Cucco Lady doesn't mean she can also be someone else's counterpart. In an edit, I will explain about the possibility of Anju and Princess Zelda being counterparts.
Edit:
Onto the Anju and Zelda possibility:
The Ocarina and Time and Pendant of Memories bit for Link and Kafei can be used here for Anju and Zelda.
One of the things that make them similar is there mind-set. Both Anju and Zelda believed they will see their precious ones again. During the flashback with Zelda, she says "And I believe in my heart that a day will come when I shall meet you again." If the Anju and Kafei sidequest is done correctly to the end, you will find out that Anju has stayed at the Stockpot Inn, knowing that Kafei would come back to her, and he did.
I think that's the only thing I can think of right now, so if I find anything else I'll include it through an edit.