Thanks for the advice but I already tried that and even with the "/" at the end the icons are not displayed properly. I've been speaking with Alias Support back and forth via several email letters and they have notified me that my bonus tools bug is reproducible on Linux but since they don't officially support Bonus Tools the bug will be listed as a low priority. So at least I know I'm not the only one with this bug and Alias Support will eventually find a solution.
As a side note I recommended to Alias that in future releases of Maya whether as an update or the next full release to include Bonus Tools as part of the Maya package. This would mean Alias would officially have to support the package but in essence they already have a responsibility to since they offer the download from their website. Hopefully we'll have soon not only a working Bonus Tools for every platform but also if we are lucky some tools from Motionbuilder since Alias has recently acquired the company Kaydara.