[einpoklum]

This format is terrible for working with line-based tools; you need to go an unknown number of lines back to get the date or the time.

Although, TBH, the OP's suggestion of one-line-per-day puts too many items on the same ling. I would have gone with one line per event. Yes, there's more repetition, but you need no out-of-line context, you have to do a lot less parsing, and you can look at a fixed number of _columns_ and get the beginning of the description of each event, which is nicer for manual searching.

[bArray]

I think it's somewhat passable with line-based tools, i.e. you could easily use sed to match a range [1].

I think that it's far more important that it is human readable, if it becomes too tricky to edit manually, then just go with a database.

[1] https://unix.stackexchange.com/a/236754