Hi there and welcome to UKAPS.
By Plecoptera I presume you mean Plecostomus? If so, your Riccia on wood won't last very long as most Plecos tend to lie and graze on the wood. If he grazes on wood with superglue fixed to it then i'm sure that it will be less than ideal for the little fella so personally I won't bother. This obviously only applies if you meant Plecostomus, if you didn't then i'm sure it will be fine, I would however suggest fixing the Riccia to your wood using fishing line or a hair net.