DISCLAIMER: These notes are from the defunct k8 project which precedes SquirrelJME. The notes for SquirrelJME start on 2016/02/26! The k8 project was effectively a Java SE 8 operating system and as such all of the notes are in the context of that scope. That project is no longer my goal as SquirrelJME is the spiritual successor to it.
Comments before a specified character to the start of a line would complicate the tokenizer and I am not sure of any languages that actually do that.
And making whitespace single characters simplifies parsing greatly because no complex work is needed when most whitespace will always be a single character anyway.