→ all versions of this pipeline
You kept the walk for other stories but said it competes with the story at times. Three quieter versions, on the whole of episode 1, each still passing every delivery check so you are judging finished episodes rather than sketches.
You already told us what “does not compete” sounds like when you chose the storybook. Both beds sit at the same overall loudness, but the walk puts 3.9 dB more energy into the range where your voice and the children’s live. Bringing it down to the storybook’s share of that range costs about 3.9 dB. So the middle setting here is taken from your own decision, not from a model.
The measurements do not settle this and are not pretending to. Across the whole 5 dB the masking figures move less than a decibel, because they compare against a moving reference. What you heard was a tune competing with narration, and nothing here measures that. Your ear decides.
If 3.5 is still too much, take the 5. It is already made and it passes, so there is no need for another round. Below that, level stops being the right lever: the fix would be new music aimed at a different register, not a quieter version of this one.