Force ability sensitivity has long been established as something of a training thing, like yoga, to use a hippy example. (sorry, but its true the hippy thing, and that's cool.)

That doesn't mean anyone can become a full-fledged Jedi, but it does arguably allow anyone to teach themselves to "attune" themselves to the Force, to better listen to the Force and be sensitive to how it moves, without ever becoming or being a Jedi, Sith or some extreme-acrobat flinging lighting and crates about. There is this thing called midichlorine or midiammonia? Which is connected to how well you can listen to, commune with and potentially manipulate the world through the Force.

The RO visual guide tells us the following: "Deeply spiritual Chirrut Îmwe believes that all living things are connected through the Force. His sightless eyes do not prevent him from being a highly skilled warrior. Though he seemingly lacks Force abilities, this warrior monk has rigorously honed his body through intense physical and mental discipline." (My italics.) The last sentence supports the training side of things, and also neither confirms nor denies his Force sensitivity, or level of attunement, it is still an open question, probably/possibly to be covered more in-depth here: http://makingstarwars.net/2017/01/star-wars-novel-guardians-of-the-whills-to-explore-chirrut-imwe-and-baze-malbus-backstory/

Furthermore he has an "echo-box" that "assists in situational awareness".

So he "seemingly" lacks Force abilities, he has technological gear to assist him. This clears it up to me, he may have FR 1, if the player wanted to give him access to sense and/or farsight. I believe farsight works well here, as in one of the scenes after he kicked serious behinds, its as if the duration upgrade ran out as he doesn't notice the new batch of stormtroopers arriving. If as a PC he has FR 1, it's probably from emergent or exile, bought after Martial Artist from No Disintegrations.

The visual guide also mentions his martial arts style, which seems together with another paragraph on page 90 of the RO visual guide, to underline his ability to hear people and the environment (at least within short range, in most encounters) and navigate it.

Anecdote: I spent one day in complete darkness a few years back as part of a scenography course. Throughout the day we were guided by a blind man, and I must say, some of us became quite good at navigating the room and each other after a few hours in complete darkness. I'm not saying we became (or could ever become) Chirrut or Zatoichi (or Daredevil for that matter,) I'm just saying, you can hear and feel stuff around you. Lack of vision is limiting, but you're not without sensory input. And your impression of someone without visuals can be quite extraordinary - we didn't see the guy before at the end, when they asked us what we thought he looked like. Suffice to say, we were all way off! Which goes to show how easily and hard we judge people based on appearances ... and I'll stop my digression here.

In short though, the game doesn't really differentiate between force sensitive or attuned to the force - as these things indeed seem to be different. But I'd say a character with FR 1, perhaps 2, could pass as someone "merely" attuned, as long as they only have force powers that enhance themselves.

If we are to create Chirrut in this game you either have to go for Force Rating, or you have to get hold of some gear and perhaps create a custom skill, that allows a non-sensitive character to emulate an attunement to the Force.

An echo-box could function something like an FFI-thingamajig. It could have a passive function: Downgrading and/or reducing setback dice for being blind but this adds setback dice to Stealth checks, because, you know, sound. It could have an active function with a similar mechanic, but with a cost of one manoeuvre per round to be able to ignore portions or all of the penalties from being blind with in [range]. Or it could be one action in one round as perception check, which allows the wearer to ignore penalties for being blind within [range] for a number of rounds equal to X - where X could be ranks in perception, cunning, or something else. Or it could be something completely different.

A custom skill could be called Blind-fighting, which for example could be limited in the following way: can never have more ranks than you have in Perception (or some other skill or characteristic.) The skill can be passive, i.e. ranks downgrade difficulty due to blindness/concealment, if the character possesses more ranks than challenge dice in pool, the remaining ranks removes setback dice ... I must admit, this mechanic is not in line with FFGs design, which is due to my delve into HARP SF these days. Skills are supposed to be rolled. This wouldn't be a skill you rolled if the mechanic was passive.

So an active version may be better, but how that would work I'm not sure, as it seems all cool things comes from talents in this game.