Runners Retouching After Foul Ball?

 
There are no outs and runners on second base (R2) and first base (R1). The batter and pitcher are in a good "duel" with the batter fouling off numerous pitches. On each of those uncaught foul balls, R2 returns to second base to properly retag. However, since R1 is not being closely held by the defense, R1 is returning to only about 6-8 off first base and not properly retouching first base after any of the foul balls.
 
The defensive coach quietly reminds the umpire that all base runners are required to properly retag their bases after a dead ball (such as an uncaught foul ball, NF 8-2-2). The coach appeals that R1 should be called out.
 
What do the umpires do now?
 
Call
By rule, after an uncaught foul ball, runners must return to their appropriate bases. The plate umpire should not put the ball back in play until this requirement is met (NF 8-2-2).
 
However, there is a generally accepted interpretation that runners need only return to the "vicinity" of the base - close enough so that they do not have an advantage in advancing to the next base when the ball is made live by the plate umpire. If, in the umpire's judgment, a runner is taking unfair advantage of this "vicinity" interpretation, the plate umpire can require a runner to retouch their original base before the ball is made live.
 
In the situation below, there is no appeal available, and there is no penalty.