Specifics
The containment zone is to be expanded as needed to accommodate for all growth and expansion of SCP-XXXX. The containment zone is to be kept free of all wildlife.
Is there a reason the Foundation wants to keep increasing the number of contained instances? As opposed to containing a set sample, and simply destroying any further instances encountered outside of containment? Also, perhaps describe what wildlife exclusion measures are in use (fencing, bird nets, noise deterrents)?
Instances of SCP-XXXX-1 are 1 cubic meter kingdoms that appear to be made of clay and/or plastic.
'Kingdom', I think, basically refers to everything under the rule of a king/queen. 'Castle' would more clearly indicate that specific type of structure. Also 'appear to be …' Can the Foundation not do some kind of test to identify the material?
SCP-XXXX-1 are found on store shelves in a glass tank.
Glass is heavy and fragile and not very efficient packaging for something that doesn't require it.
The culture of SCP-XXXX-2 consists of a basic monarchy. SCP-XXXX-2 will follow a ruling individual from their original instance of SCP-XXXX-1.
I believe a monarchy would have a single head of state. This sounds more like perhaps some form of feudal tribalism (?)
SCP-XXXX-2B are more intelligent than SCP-XXXX-2, possessing the basic knowledge of a 25 year old adult human.
This comparison is not effective. Like, a 25 year old university-educated doctor? A 25 year old illiterate dirt farmer? I thought there was some sort of guide/essay on the matter (which I can't find just now), but this forum thread may be helpful for how best to describe the skip's assessed intelligence.
Overall
Firstly I must say, that looks to be an impressive amount of work put into the building of the language and whatnot. Though I must also admit that a lot of it is over my head, so I can't definitively say how much it adds to the article.
I might suggest changing the order of the information given in the article, so it begins with the basics (general description, appearance, origins/discovery) and then work towards describing the finer details (advanced physiology, society structure, language). So the pace and progression will keep readers interested without getting ahead of itself or moments of 'information overload'.
Also, when it comes to describing the general structure and specific traits of their society, I might suggest some research into the general practice of anthropology. This should enable you to more effectively categorize the different aspects of the skip's culture, and maybe to use more terms that will add to the feel of authenticity.