It started with 1.2.6 and would quickly get stuck in under 30 min. Tried 1.2.6d before the first comment, and it did take a lot longer (>1hr) but Darian did start doing the "X (unit of time) later" thing and wouldn't stop.
Try setting shortTermMemoryClearingEnabled to true in AppData\LocalLow\Three Eyes Software\Silverpine\settings.json and waiting at least 12 ingame hours after. It eliminates these kinds of issues, but it's turned off by default because it reduces character consistency. If it wasn't a problem before, it's because Nemo was paying less attention to things, including any repetitive behaviors.
Was able to go for quite a while without Nemo ever doing any of those annoying things. The character consistency was noticeably worse but at least the conversations weren't getting derailed because someone mentioned a number or the passage of time.
Now if only I could figure out how to get the AI to have the character actually follow me instead of role-playing that they're following me.