changing the shape of one cycle of the waveform can have little effect on the sound heard, see … https://forum.audacityteam.org/t/is-there-any-way-to-remove-this-warning-from-the-draw-tool/47219/4
If there is a formula for your “custom waveform”, try this “ExpressionGenerator.ny” plugin …https://forum.audacityteam.org/t/expression-generator/45227/1