I like the idea of the circumfex marks being body language translated into symbology. I imagine each circumflex to be a different gesture with eyebrows, beard, shoulders, ect... which would make the spoken Dwarvish to be a very animated language.
The abbreviated word list I've often imagined to be only the spoken version of it, and incomplete for much the same reason as written Hebrew did not contain vowels: the reader was assumed to already know what was needed in the spoken form and add it into the "short-hand" written form.
As such, my conjecture is that the word list we are painfully trying to reconstruct is not the full language, but merely the verbal form, the rest being positional/gestural in nature. It's my contention that while dwarves are industrious, they usually have to get together in "parties" to actively communicate - dwarves will not transfer information unless very near to each-other, indeed, "line-of-sight" is required for information to pass between them. So - the written form would necessarily contain "gesture marks" that have no phonetic equal, indeed, attempting to pronounce a gesture would be untranslatable to the dwarven ear and not making the proper gestures while doing so would trim all of the verbs, prepositions and the like from the language, making it (understandably) incomprehensible.
Considering that often dwarves communicate while holding things, a hands-free series of gestures and relative body positions, such as "leaning toward (the conversational partner)" or "leaning away from (the conversational partner)", would be more likely. Head, hip, shoulders, elbows, knees and feet positioning increase the ability to convey information non-verbally in conjunction with the verbal aspects of the language.
It's interesting to note that such a form of communication would lead to a highly individualized fighting style, since group consensus would quickly deteriorate into individual action/reaction cycles until such time as the vocalized shout is heard and recognized as a general positional change requirement, which is in line with how we see dorfs fight and train.
(Of course, this would make dwarves in a passionate discussion, such as when electing a Mayor, seem to be suddenly overtaken with mass seizures.)