Bans happen, any scripter who is going to advertise their scripts as being undetected or unbanable are lying to gain more sales from gullible customers.
I have a disclaimer that alching and cannoning is more dangerous than just cannoning. As I believe the more afk a script is the better are your odds to not get banned, if you increase your actions per minute by alching you have to compensate for that in how long you bot or how many breaks you take.
The best advice I can give you is to limit your botting hours and to use mirrormode to improve your chances of not being banned.
If you want to read a more qualified opinion on bot detection and avoiding bans feel free to check out this post made by the previous OSBot client developer. It also addresses your concerns about implementing "humanlike" behaviour like randomly moving the screen.