My own timeline project was a database in Superbase 4, back in the late 80s/early 90s. I still have it, and of course we will be incorporating it into the Database. Here's my idea of how to do it:
mdb_timeline
id
alphatian_year
thyatian_year
description
mdb_source_id @
source_page_reference
mdb_officialness_id @
By including source and officialness, we can input all the various timelines without worrying about continuity.
If we decide to implement a compatibility/continuity field, we can add it too.
It would also be possible to add a tagging system for timeline records, to note their subject, although keyword searches can probably cover this without any tags.
Lastly, we might want to add an "Importance" field (inconsequential, minor, major, world-shaking), to document how important an event is, and to allow for the easy exclusion of certain kinds of events in a query. It would also allow events to be ordered from most important to least important in any output.
Edit: We might want to allow records to have multiple sources, since quite a few are repeated in various sources. In that case, the tables would be rearranged as follows:
mdb_timeline
id
alphatian_year
thyatian_year
description
mdb_officialness_id @
mdb_timeline_source_linkage
id
mdb_timeline_id @
mdb_source_id @
source_page_reference
Another thing to consider: we will probably need month and day added to the table too, to cover Wrath of the Immortals, the Poor Wizard's Almanacs, and indeed the Mystaran Almanacs.
