Anything (ie. crow's foot) that effectively increases the moment arm of the force/leverage applied to a fastener by a torque wrench in fact applies more force than the reading on the wrench. This is an absolute fact.
About the adapter or extension thing though- you all have got me thinking about this and I definitely have no answer to this as yet. Take for instance an extension that is, say, 20 feet long (extreme illustrative example). At least at higher torques that extension will twist along it's length, which I guess you would call torsion. The question I would have is this- is the force at the end of that extension equal to that which is originated at the wrench end? I don't think anyone has, as yet, examined/explained this here, at least not for me. Even if this torsion does indeed effect the force value, I surmise that using an adapter or short extension has negligible/inconsequential results.
But hey, whadda I know? I'm just a dumb carpenter.
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"I tell you, We are here on earth to fart around, and don't let anybody tell you any different." - Kurt Vonnegut jr.