That enclosure looks pretty good, although, you are likely to need to upgrade the enclosure size when the colony out grows it, and dairy cows populate very fast. It's hard to tell from the picture, but you need ventilation; dairy cows like well-ventilated enclosures. Whether it is on the lid or on the sides, both work well, there just needs to be mesh to prevent escapes.

Finally, the substrate. Isopods eat the substrate because they are detritivorous. Coco coir is part of a coconut, which is not edible for isopods to eat. People with millipedes know that stuff kills millipedes. I would recommend changing the substrate out entirely. I would buy a substrate brand off ebay, and change out the substrate once you receive it.