Editor numeric input fields don't support double precision numbers.

Even if we support double precision numbers at core, it's impossible to enter a small number in the numeric fields. 

It makes sense for floats and avoids bloating the UI, but I remember a discussion on this topic a very long time ago for UE5.0.
There was a problem with string conversions IIRC. Have you had recent discussions about this with the UI/UX team?The licensee needs to enter small numbers (it's for railroads' radius of curvature, so yes, precision matters).
As a workaround, I told them to use String properties instead and do the back-and-forth parsing themselves, but this is just a workaround.Side note: Even trying to trick the system with an expression like "0.00001/1000" ends up truncated to zero... That would be great to evaluate expressions in doubles before setting values

Entering a small number in the details panel numeric field like a position
It's not possible; it's truncated to the 7th decimal  (0.0000001 --> 0)