1. I made a minor change to the titles of the posts, including the (rough) date that the writing system came into existence and what (modern-day) country it appeared in. (The country will need to be approximate. Usually the exact latitude/longitude isn’t known.) Note that where it appeared and where it is currently used can be very different. Bopomofo is currently only used in Taiwan, but it was developed in the area now covered by the People’s Republic of China.
2. I have made other minor changes to posts — fixing typos, improving wording, etc.
3. I haven’t edited the posts to show that I made changes. There is one ethos that says that in dated posts, you should always be clear about when you change it retroactively, that otherwise you are dishonestly claiming that you said X on date Y when in fact you said X’ on date Y.
In general, I agree with that for substantive changes. However, I don’t think grammar and wording tweaks are (usually) substantive. Furthermore, this blog doesn’t cover time-sensitive material, nor is it a highly competitive area. This is in a blog format because it’s a convenient mechanism to dole out bits of information one-at-a-time, not because it is breaking news. Nobody’s career is going to be made or broken if I add a paragraph to Sumerian Cuneiform a month later about what the species of reed the Sumerians used to write with.
At a more fundamental level, I don’t think anybody really cares about this blog except me.
Thus, for edits that are fixing typos, wording clumsiness, or additions, I probably won’t mark it as an update. For edits that contradict what I said before (like if I had said that Simplified Chinese had been mandated by the Mongols who took over Egypt in 1625 AD, then fixed that), I will do my best to mark them as updated.