Seconding that, and going further: the posts that get replies are the ones where something did not work.
My most-read posts are, in order: a thing I got wrong, a number that went down and why, and a decision I reversed. The launches are far behind.
The reason is straightforward. Wins are unfalsifiable and slightly boring, and everybody posts them. A failure has detail in it, it is useful, and it is rare enough to be worth reading.
It is also why your instinct to avoid dressing up a refactor as a milestone is exactly right. Readers can tell, and the cost of being one of the accounts that manufactures news is that nobody believes the real numbers either.
So for this month specifically, I would write: here is the mess I made in year one, here is what it cost me by year two, here is what I did about it, and here is what I would do differently. That is a genuinely good post and it is available to you right now.
One practical note: do not explain the gap. Nobody noticed. An apology for not posting is a paragraph about you rather than about the work, and it makes the silence into a thing. Just post.