To elaborate on this, our screenshot isn't the first as part one seems to indicate its elements have been there, together, and only fallen into ruin.
I'm not contesting that they fell in disuse together. The question is whether they were built together. And I fail to see how you can determine that from the picture. Most castles and country estates are conglomerates of parts built in different centuries. Quote wikipedia about Castle Heidelberg: "The earliest castle structure was built before AD 1214 and later expanded into 2 castles circa 1294; however, in 1537, a lightning-bolt destroyed the upper castle. The present structures had been expanded by 1650, before damage by later wars and fires. In 1764, another lightning-bolt destroyed some rebuilt sections."
To make it clear, the timeline of our stronghold could be this:
castle built with walls ----> war,razzing, disuse ---> changed into a country house by a lower noble, walls repaired ------> disuse ---------------> now.
But, okay, I'll stop here. I feel I'm splitting hairs here over something we actually seem to agree on: the stronghold should make sense ingame, right? And to that end what we've got is far from perfect so far.
I would be perfectly fine with an ingame history that made sense. But not needing an explanation at all would be even better
As for keeping it modest, I do agree with you in principle, but the castle I posted and Mor reposted? That is a pretty modest, standard, lower tier noble, medieval castle. For more examples, take ....
Your example links point to castles, and to my knowledge castles were unbelievably expensive in medieval times. Kings or Dukes could build them, lower nobility surely not. A king could also give a small castle as a lease to someone deserving or to a knight to make some border safe.
Now we are talking about a stronghold, a stronghold aka Festung could just be some buildings inside a fortification. See Festung Dömitz as an example:
Burg Oesterode (your modest castle) is small compared to Castle Heidelberg for example. But the black and white seems to understate the size a bit. Look closer and you see that it is surprisingly large, especially compared to anything "not-castly" built in the 12th century. It was built by a king and kings lived in it. I'm no expert and I could be totally wrong, but that doesn't look like something a lower noble could have built.