@Ram_Sundar
+1,
I am seeing the same behaviour as-well. I tried the available editor settings (Autocomplete as you type, Automatic Genie Code Autocomplete, and the keyword/function casing options) and none of them changes the casing of CTE column suggestions. Can also Disable Auto Complete entirely, but that removes suggestions rather than fixing case.
Declaring the names in an explicit column list e.g. WITH test (ColumnOne, ColumnTwo) AS (...), and backtick-quoting aliases didnโt help either and suggestions still come back lowercase. Tried this at Notebook level too, still the same issue.

Genie suggested that when the editor's autocomplete reads the CTE's schema, Spark normalizes column names to lowercase internally, so the suggestions appear lowercase regardless of how you alias them.
My understanding is that the legacy editor has been retired as per latest docs, so reverting isnโt an option anymore. I tried developer settings and SQL editor settings, but couldn't find any to revert too.
It looks like it needs a product side change or a setting, so it would be great if someone from Databricks could confirm whether a fix is planned.