This is supported by Chammah which is also a word for the Sun, and sharing a root of the name Shammash (KhMH became KhMSh). Then Again for years Shammash was englished Chemosh. There is LOTS of wiggle room, the best guidance is use a "real" word in some language for the spelling, and something relative.
As for Samael meaning "poisoner of god", it is funny that KhMH an ancient proto-hebrew root means Hot, but it also translated as "Poison" in the bible, and specifally the poison of a scorpion or serpents or the poison of the lord eve, such as in this verse.
For the arrows of the Almighty [are] within me, the poison whereof drinketh up my spirit: the terrors of God do set themselves in array against me.
Etymology of Samael withstanding, I have found no proto-hebrew root. But this verse is to me the perfect one to illustrate that "poison of God" is not a bad thing, for it is a sign that his arrow hit to the soul and you are in his aweful presence.
As for the idea a word is an angel: actually, there is to the magician not much difference between the names is some context except that he knows their roots, and we see that it is more that Kamael is Geburah as dispensor to the sun of Tiphareth, while Samael (theoretically) is more the *heart* of its true severity, a wiping out of life. Regardless, both encapsulate both Madim and Geburah quite well and share a common root and concept. Khamael is proven to have older linguistic roots.
For example a burning wrath can easily bring to mind punishment and fever, and the bale sun scorched day has surely the effect of poison on the land. But the whole of Egypt was said to have come from Ham, son of noah, and it was kamael that killed the Nile, and some say it is the source of the plague of fire that was prelude to the exodus. Speculation has always been part of the magicians true set of tools.
Always remember you are dealing with people who were very semi-literate and spanning huge language barriers. They were usually working in different languages, and they were writing phonetically, according to their education but often for a varied but by no means broad audience.
Wish you well.