I don’t get the idea of most spoilers, anyway. Choose them, and nothing of great import, not a “secret” , generally what is already known, or easily found. Seem to be a way of saving space, while adding more information if someone wants to check it. Hence, why called spoiler, since it isn’t giving away the plot.
The idea for private spoilers sounds good if journaling and wish to keep something from public view. ( I do not journal, so no clue how it works)