This is the first I have heard of No 19 CCS being at Remy during this period. Everything I have read so far puts the composition of the Remy Group then as Nos 10 and 17 CCS and Nos 2 and 3 (Cdn) CCS. These four stations operated there from the beginning of 3rd Ypres through the end of 1917.
The attached snippet with the Diary of the 3rd Canadian Division shows the 2nd Army CCSs as of October 1917, and No 19 CCS is not listed at all. (2nd Army took over most 5th Army units about this time).
I am willing to be convinced otherwise, but I suspect No 19 might be a transcription error of No 10.