In recreational climbing, skin calluses and surface abrasion aren’t usually much of a concern compared to tendon health. Skin heals light damage quite easily.
However, it’s not uncommon for a new (or experienced) climber to develop their muscles beyond what their own tendons can take. Since it takes tendons so long to strengthen, it’s common to need managing the risk of finger pulley tendon injuries in climbing.
Also, I do not know how these nuances apply in your context of your medical condition.