Ake!
Looking at Tadhg O’Keeffe’s Romanesque Ireland[Four Courts, 2003], p. 329, I find a mention of the problem you have noticed at St. Saviour’s in Glandalough. He says that ” St. Saviour’s is heavily restored, its lovely stonework disfigured by calcite from the late nineteenth-century mortar” ..though the “restoration seems quite faithful to its original appearance”.
T. O’Keeffe dates this Augustinian priory church to some time between 1153 and 1162 while Lawrence O’Toole was still abbot.
So, I suppose the only way to solve this problem -before it completely erodes the stonework- is to take ita all apart again and rebuild it without the problematic mortar. However, can we expect that the OPW is up to this – given what they have been at on Cormac’s chapel. Speaking of which, any updates on that question?