Hi @Anonymous
I havent really tried changing the material in the library because my librarys are read only and I don't have time right now. But I could change the comments in the documents local material using the commented out code below.
I think you should try something like this (uncommented out) and see if it works 🙂
Dim oAssetLib As AssetLibrary
oAssetLib = ThisApplication.AssetLibraries.Item("TIF Material Library")
Dim oAsset As Asset
oAsset = oAssetLib.MaterialAssets.Item("Steel 0202")
oAsset.Item("physmat_Comments").Value = "Comment goes here"
'---------------------------------Test------------------------------------------------
'ThisDoc.Document.ActiveMaterial.Item("physmat_Comments").Value = "Comment goes here"
'-------------------------------------------------------------------------------------
Edit: I took the time to test it on a material in a read/write library and it works!