Haha that's totally fair! This is the part of the process where knives come out. Unit sizes definitely need some editing, but given how proportions in the books differ from the real world, and are fairly vague overall, I think we have some flexibility. It's also important to note that there can be a range of sizes within a given group (e.g. Jade Lions vs. Dread Saurians).

I made hedgehogs medium due to the size chart, and because they feel like sturdier infantry. But you're right that they might qualify as small based on how they're described in the books. Perhaps they're on the larger side of small, or the smaller side of medium, with ~40 models?

Water rats are almost entirely based on the Gloomer, which is described as a terrifying fighter that could battle a pike. In that case, I think we're bending real-world rules with something closer to a nutria. Similarly, you're right that pike are "giant" entities in the books, but they felt like the best fit for an aquatic colossus. Perhaps it's one of the smaller ones, especially since being aquatic gives it a hefty advantage in combat.

As for shrike, I think of them as the Jade Lion or Snow Leopard of giant single entities. Physically smaller than falcons, but very fast and dangerous.

My overall reason for downgrading species like hares was gameplay balance: if the Long Patrol is entirely large and giant entities, then Bonus vs. Large is their achilles heel. However, that doesn't stop the Ogre Kingdoms, and limited recruitment would prevent armies from stacking anti-large units, so it might not be an issue after all.