Dear Prof. Sudarsky,
thank you for your feedback and your very interesting comments on the minimal requirements for a (empirically adequate) measurement process.
Let me instead start my reply in inverse order with respect to your question:
1. Stabilty. Your concerns are torally right, and I should have been more precise. What I had here in mind is an axiom similar to that of quantum mechanics. Namely, the state of a system remains unchanged when it is not measured, modulo a unitary evolution. I was here assuming the trivial evolution and focusing only on the chenges of the states due to measurements.
3. Precision improvability. Here it does not need to be at the same time. I am again thinking of repeated measurements on the same system. If even time is smeared and not sharply defined, there is an operational procedure that we call measurements that returns a certain number of digits. If one improves the precision of the measurement (dividing into ten a ruler, for instance) we should be able to find a new digits. However, all the previous determined digits are required to remain stable.
1. Intersubjectivity. I think what you say about this is a good point. Indeed, admittedly time remains the most difficult issue of our FIQs framework. At least, if one wants to determine a quantiti which does not depend on time (a natural constant of physics, for example) this must apply. Then, to compare two dynamical quantities at the same instant, is indeed not fully spelled our in our model.
I inted to wrote ore about general processes of measurement in non-deterministic theories. I will treasure your latter criticism to clarify this matters.
Thank you again and best wishes,
Flavio