[Venish Paneliya (VenishPaneliya)]

Why are these changes needed?

Two docstrings in flaml/automl describe things the code does not do:

• DataTransformerTS.fit has a Returns: section listing processed X and y, but the method returns None — fit_transform is the one that returns the transformed data, so X, y = transformer.fit(X, y) raises a TypeError.
• norm_confusion_matrix documents an estimator parameter; its signature is (y_true, y_pred).

Both are rendered into the API reference by pydoc-markdown. Docstrings only, no behaviour change.

Related issue number

None.

Checks

• I've used pre-commit to lint the changes in this PR (note the same in integrated in our CI checks).
• I've included any doc changes needed for https://microsoft.github.io/FLAML/. See https://microsoft.github.io/FLAML/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed. — pre-commit-check fails on main too, see the comment below.

[Venish Paneliya (VenishPaneliya)]

The pre-commit-check failure here is unrelated to this diff: pyupgrade v2.31.1 crashes at import on the runner's Python 3.14 (AttributeError: module 'ast' has no attribute 'Str' — ast.Str/ast.Num/ast.Bytes were removed in 3.12 and the deprecation shims are gone in 3.14), so it never looks at any file. black, mdformat and ruff all pass.

It looks like the runner image rollout rather than this branch — #1661 hit the same failure on 2026-11-10 while other runs the same week passed. Happy to bump the pyupgrade rev in .pre-commit-config.yaml in a separate PR if that would help.

The failing build (ubuntu-latest, ...) jobs are also unrelated: every error is PySparkRuntimeError: [JAVA_GATEWAY_EXITED] / Py4JJavaError while starting the Spark context, so the whole test/spark directory errors at collection. #1660 and #1661 show the same failures on ubuntu runners. The Windows jobs, which skip Spark, all pass here.