An opinion...
Accidents happen. She needs not know anything. R's apparently been riding just fine all these months so being involved in a single crash that a witness says isn't his fault shouldn't be a big deal. If she makes a bigger stink about it you'd think the club, being more familiar with both R and the witness, would be more likely to shut her out than him. It would be in her best interest to review what really happened in her head and figure out how to avoid future collisions than to simply point fingers like a little kid- 'He did it!'. Hopefully she does so she can continue riding- and learning how to ride with -the group.

So......
will she be upset about (it?) Yes, if she's the sort to throw blame about, but only because she can feel justified.

and will she be justified? NO.