Looks good

.
It occurs to me that 1,2 were using cpctelera 1.4.0 and 3 was 1.4.2 and only 4 was on a version of 1.5.
That suggests to me that the API has been very stable.
I can see merit in updating projects to the latest version but I haven't really seen much need.
Perhaps there is a way you could allow the speed to be tuned as a wincpctelera specific function or something.
Or I could just put a dodgy wait in to fix the problem.
That said because it is last years project I am not really likely to touch it again unless I wanted to port it to another platform or something.