Something I wrote in a comment was wrong! I said that the two letter 'R's which, in Bessler's alphabetic substitution code, stands for the two 'E's, which are the initial letters in two of his forenames, could also represent the number 18, the base angle in a pentagon - because ithe letter 'R' is the 18th letter in the English alphabet., Oops! Bessler's German alphabet consisted of only 24 letters, I/J and U/V being alternatives - which means the letter 'R' is the 17th letter not the 18th! So it has nothing to do with the pentagon.
Johann Ernst Elias Bessler - J.E.E.B., through the ATBASH cipher transposes to W.R.R.O. So, I think that the two 'E's can be taken as representing the letter 5, being the fifth letter of the alphabet and also because Bessler has used that same alpha-numeric code in numerous other places. In addition I think he intended the letter 'E' to point to the letter 'R' because he used alphabetic-substitution in many other places too.
His name, Johann, added at the time he added Elias, seems a mystery addition unless you accept that with alphabetic-substitution Bessler meant to point us to the letter 'W', which also has no alpha-numeric meaning either, being the 21st letter of the German alphabet - but it is a useful pointer to the number 55. This is because of the way Bessler always wrote it - as two overlapping 'V's, as in Roman numerals, which he also used frequently.
So the letter 'J' itself, seems to have no underlying meaning but what about the the letter 'R'? Maybe the 'R' does have a meaning. Bessler always signed his name accompanied by a little avatar or logo. It consisted of a circle with a dot in the middle supported by two letter 'R's each facing away from the circle
They are not complete 'R's but you can see that the two curved figures are meant to represent the letter 'R'. It looks as though there is no alpha-numeric meaning to be extracted from the 'R', but it does seem to have purpose, I think it shows a movement of a part or all of one mechanism. Here's another example from maybe 50 which I have and although there are variations in them most have the two 'R's and a circle.
But the letter 'J' really doesn't seem to have an additional meaning - unless I have missed something?
In summary, J = W = 55 and E = 5 = R = ? Not much information there, and yet it's in such an important place, i.e., his name - it must be of importance.
JC