I'm assuming that is a 47 cm Atlantis? As I believe Rivendell has never made a 48 cm version of the Atlantis.
A non-Riv, but extremely-close-to-being-Riv option would be an
X-Small Crust Romanceur. It's a rim-brake, 650b, fully-lugged bike in the style of Riv. It has an 40mm shorter effective TT than the 47 cm Atlantis. Giving it 30mm less reach (365 vs 395). It has more than a flat-ish TT, it's level! But that might cause some stand-over issues? You can compare them on
Bike Insights and see that the Romanceur is quite a bit the smaller bike of the 2. And as for "light-medium touring loads", the Romanceur is a beast and can easily be a fully loaded off-road touring bike... but is also great on the road. It's a great all-rounder (again in the style of Riv). However, all my experiences are at the opposite end of the spectrum: I'm 6'3" and ride an XL version of the Romanceur... So apologies if I'm missing some nuances of bikes for my more diminutive bike friends :)
(Final note: The CEO of Crust bikes is Cheech, who is herself a diminutive rider. I know that because of her they go out of their way to support that often overlooked market. They might have additional info/experience in sizing X-small bikes).