Cannot join CraftBukkit 1.5.2 server from 1.8.9 client

[sys128]

General Information

Custom Hand GUI Mod, ViaForge, Optifine

Bug Description

Despite setting the ViaForge version to 1.5.2, I get immediately disconnected from the server, and in the menu, the connection meter is crossed out (with Client out of date! message) as if I have selected the wrong version. I can join a Paper 1.20.1 server with no issue.

Steps to Reproduce

1. Load the ViaForge mod with the 1.8.9 client
2. Set the version to 1.5.2 from the ViaForge menu
3. Attempt to join a 1.5.2 server (The one I was attempting to join was running CraftBukkit)

Expected Behavior

I should be able to load into a 1.5.2 server just fine.