Just curious, why is it that the experiment/trial boards are only on Wakachan and not shown on iichan as well?

Some of them are, but they're mixed in with the rest.

Experiment is for new(er) boards, to highlight their existence. If they get popular, they're moved down to a more appropriate section. If they don't, they stay for a while in Experimental until they're removed.

I have to clean it up some time in the next week or so.

Fair enough.
Though it's a shame that the Key board hasn't been all that active as of late.