The cancels on the block are genuine; the cover is forged to me. Point 1 is well taken but it's hard to make a decision off this scan as always, for me at least. But I would lean toward it being partly drawn in. Point 2/2a I think definitely makes this a forgery. Point 3, the partial cancel at the right on the block slipped a bit so I would not say the misalignment is useful info.
Now the reason I say the cancel is genuine is that I found the following on several blocks from a sold
ebay lot:


Same date, style and city as the block on the cover. The same month /day date is shown in Rod's reference of the type 13 though the cancel is probably type
19 18 with year date "19" in western style; the blocks above have the check/control/device number 2. Not a coincidence as there are other blocks so cancelled (same date and type); singles can be found elsewhere too. We know Cilica stamps were favor cancelled/CTO; there are a fair number with gum and a lot of singles that have nice corner cancels.
So, yes, I'm pretty sure this a cancelled/CTO block of the 5pa stuck on on an envelope with a mint 10pa single, and the cancel drawn in to tie stamps to the cover.