Does FEATURE_V_1_2_SAFE_FUNCTION_CALL language feature actually work?

I'm trying to parse a query that contains a safe function call with this language feature enabled, but I got error saying `BigQuery resource not found: project-id.SAFE.FUNCTION_NAME`. Related to https://github.com/GoogleCloudPlatform/zetasql-toolkit/issues/109.

Here it's stated that the language feature enable safe mode for function calls, e.g. `SAFE.FUNC` for `FUNC`:
https://github.com/google/zetasql/blob/a516c6b26d183efc4f56293256bba92e243b7a61/zetasql/public/options.proto#L850-L852

But the test case for that language feature doesn't cover `SAFE.FUNC`, instead it only covers `SAFE_FUNC` function call:
https://github.com/google/zetasql/blob/a516c6b26d183efc4f56293256bba92e243b7a61/javatests/com/google/zetasql/AnalyzerTest.java#L526-L545

So, does the language feature has been proven to be working as intended or not?