I2 Localization & Assembly Definition

Hi. I have a project with several modules in their own respective AssemDefs and they aren't able to see the I2 namespace. I tried defining an assembly definition for I2 and another for its editor folder (both referencing each other to resolve the subsequent errors) but now I'm getting an error when I view the LanguageSource files

Instance of LanguageSourceInspector couldn't be created. The script class needs to derive from ScriptableObject and be placed in the Assets/Editor folder.

Nevermind. Restarting the editor fixed it. I'll keep this here for future reference.
forum.unity.com/threads/custom-editor-inspector-bug.579088/

Did you not get a cyclic reference error when referencing the assembly definitions files with each other?

What worked for me was the following (including TextMeshPro):

1. Add an Assembly Definition under the I2 folder (root folder) e.g. I2AsmDef and in the inspector, edit its Assembly Definition References to include Unity.TextMeshPro. I also had 'Any Platform' enabled.
2. Add a second Assembly Definition e.g. I2EditorAsmDef under the I2/Localization/Scripts/Editor folder and in the inspector, edit its Assembly Definition References to include Unity.TextMeshPro and the I2AsmDef assembly definition created earlier in step 1. Deselect all platforms and only enable 'Editor'.

You may have to quit and restart the Unity editor to resolve any reference errors.