There is no Bugs (or Possible Bugs) forum in MaplePrimes at all.
Why?

1) Report a bug using this link
http://www.mapleprimes.com/scr/add
isn't encouraging, because nobody (except maplesoft staff) will know who found the bug.

2) I think that in most cases reported bugs are not bugs, because it might happened only because user didn't know something (eg, use add instead of sum with Vectors or Matrixes).
So other MaplePrimes users could point it out without disturbing maplesoft staff.

3) Maybe the bug is already discussed in the forum, so there is no need to report the same bug and if you have something more to add then you could join that discussion.

4) Also other users (or the staff) might post a workaround for that bug. And other people would know it.

5) Just found an interesting purpose of this page:
http://code.google.com/p/mathematica/wiki/Introduction
(Introduction to Mathematica bug list)
MaplePrimes could do something similar.

6) Some forum for Matlab bugs:
http://www.mathworks.com/matlabcentral/newsreader/search_results?search_string=bugs
http://www.mathworks.com/matlabcentral/newsreader/view_thread/235448
(BTW, notice how fast is that forum - why MaplePrimes so slow? Maybe your database using wrong engine? MyISAM is faster for forums than InnoDB, because it reads data from database faster, but it shouldn't be a big difference if your database is small)

7) I will report a tiny bug here:
- open Maple 12 Classic
- Help / Topic Search
- type choose
Problem: no results!
(the same is when you type and mark word choose and press F1)
In previous Maple versions there was no such problem with the help on combinat[choose]. At least it really works in Maple V R5 and Maple 7.

8) I have some collection of possible bugs collected in several years, but I didn't find a proper forum to discuss them.