The format allows for variable granularity and ranges. If Grandma were visiting for a week, it would be fine:
2021-02-20 w07
Right now, the range (start-end) can only be hours, but changing that could fulfil your requirement, e.g. 2012-02-20 w07 Mon-Fri Grandma is visiting
> grepping is really not how most people interact with a calendar.I don't think the creator ever suggested for one minute that this is a calendar for "most people"! Most people don't use Linux, macOS, or a command line.
> sorting by date must be done manually, my god.
| sort
is not much of a hardship. At least it's possible, unlike a typical GUI app that doesn't support sort.