There are a number of scenarios where D could be read as t, so my reading of XDC.D as Matthew could work (e.g. as ma-t, mat-t or something similar). However, nothing in my simulations seems to let me read CO.IH.D as Luke.
I agonized over this for a while, then went back to the page where I tried to relate scriptural references to images. I realized that the only strong evidence for reading CO.IH.D as Luke was the triple scriptural reference, and that reading was based on the assumption that the references were to canonical gospels. But if that assumption was wrong, then there was really very little reason to read CO.IH.D as Luke.
Indeed, an image accompanying a reference to CO.IH.D chapter 6 is problematic, since it features an angel (or perhaps a winged Christ) appearing to a man lying on the ground, and I could not match that to anything in the sixth chapter of Luke.
So what would it mean if CO.IH.D is not Luke?
Looking at the images corresponding to CO.IH.D, each one involves a figure with a striped turban and a beard, twice with wings, usually with one other person, though sometimes alone outside a city. Chronologically (according to chapter) the images can be arranged as follows:
Elsewhere (e.g. in the image of Jesus entering Jerusalem) the figure with the striped turban and pointed beard is Christ, so whatever CO.IH.D is, it would seem to contain a gospel-like narrative of the life or ministry of Christ.
There are any number of candidates among known apocrypha, but I suppose I should start with anything that mentions angels in the first and sixth chapters, or else mentions Christ appearing in the form of an angel.