Is there any nuance between 'laut' and 'zufolge' in terms of usage/suitable context? I have the following understanding: 'laut' is used when conveying a fact stated by a source (study/organisation...etc.) 'zufolge' is used when deducing an act/measurement that has to be taken based on a fact provided by a source. Is this correct? Or can the two be used interchangeably?
laut and zufolge are close synonyms as you have already stated - I would only see a small difference between them, based on the words they are derived from:
- "laut" simply means someone has stated a simple fact, you are repeating it
- "zufolge" means the argument may be more complicated, and consists of a number of statements or a train of thought you need to "follow up" with.
No, both prepositions mean that you are repeating a statement from a third party and cannot personally vouch for it. In that respect the two words are interchangeable.
If I had taken my own measurement, I would say
Nach meinen Messungen beträgt die Lücke 3mm.
You wouldn't use zufolge to report your own measurement, unless perhaps you'd taken it long ago, noted it down in a diary, and are now talking about what the diary says rather than what you saw.