Hello rw123,
Welcome to the CDR forum
You're quite right. Masks cannot be saved as presets. The "presets" are adjustments made either globally or to a selected region (mask).
I'm sorry you're discouraged, but the most typical common adjustment made to videos is colour fixing & modification - hence presets.
If you need to apply the same mask to multiple videos you could combine them and produce them as a single video file. Then you could apply the mask/adjustments to the newly produced video.
PIX
PIX YouTube channel