I suspect it's down to the debugging support, and if you disabled all debugging C would be at least as small as Pascal.
I suspect you are right. At least one vendor I knew used a different front end and the same back end for Pascal and C.
Such things are available in most PC HLL's, but need to be used with great care.
From what I have seen support is not uniform. For example C18 does not have inline function. Swordfish Basic does not support recursion.
I did Forth a long time back as well, it never impressed me very much at all.
I do not know many who are luke warm about forth, often it is a love it or hate it deal. I view it as roll a your own language kit. To some extent you can do so with many languages but forth takes it to the extreme. It shines for AI work.
A few years back they dumped the screen concept. That made working with forth better. But anyone who can not get into RPN notation will always dislike forth. A few weeks ago I found a forth for the PIC18's called flash forth. Is is interpreted (compiled forth does not make much sense to me) and uses flash memory to hold the new words/code. I played with it a bit. I have forgotten much of what I knew.
It would be pretty pointless in this day and age to shift from C to Pascal, Pascal may be a far 'better' language, and forces good programming practice on you - but C has effectively beaten it off