It is debatable whether knowing about Bach's use of numbers and musical affections teaches us better how to play Bach cello suites, but it can't hurt. Bach is known to have used Numerology and the Doctrine of Affectations as a way to personalize his music and express his devotion to God.
So I wondered if he had done the same with the cello suites.
I did a bit of analysis and found a plethora of numerological and musical references.
So to answer the question...
Did Bach use Secret Symbols in the Cello Suites?
YES...without a doubt.
A simple example is the number of notes in the Sarabande of the 5th Suite. It contains 108 notes and is by far the most contemplative. The number 108 has spiritual significance in many cultures. In Christianity it relates to the pentagram (the 5 pointed star) in which each angle is 108˚. The pentagram represents the 5 wounds of Christ and the 5 joys.
In the same suite there are references to the Holy Trinity and the "Complete Bach" (i.e. Bach + Holy Trinity) which is represented by the number 41 (i.e. BACH=14 + Trinity=27 (3x3x3).
Besides this name reference, there is a musical version of his name (Bb, A, C, B natural, which is H in German). These are just a few that I found after looking at it for a short time.At some point, I may do a more extensive article with many more examples.
Just so, in my opinion this points to Bach's relationship with God which he felt profoundly. Therefore the music is very intimate and expresses his devotion. I believe this can help one to learn better how to play Bach cello suites, because it gives insight into Bach's personality and passion.