Personnally, I'm OK with these conversions. The thing is, CODA attributes are much more widespread in values than ICON ones, so having a perfect conversion could imply mathematical formulas as simple as the one for calulating warp factor TNG scale .
So, OK, it may not be entirely satisfying for a Fit 5 Str+2 human (CODA Str 14), or a Fit 1 Str-1 Ferengi (CODA Str 3). Well my view in that case is, if you really want to have a very very low attribute (or don't want it to be too high), is simply remove the exceeding points and ask the player to put them elsewhere (if a human has 14 in an attribute, top it at 12 and spend the two points on other attributes, related if possible). Such tweakings will be necessary in the conversion anyway (like the specialities, for instance, since two specialities in ICON convert as one in CODA, making a choice necessary).
On one other point, it seems to me the average for an attribute in CODA is 6, isn't it ? 4 being the low average, and below are the exceptionnally weak values. So the average human in ICON will have 6 in most attributes in CODA... works for me.
"The main difference between Trekkies and Manchester United fans is that Trekkies never trashed a train carriage. So why are the Trekkies the social outcasts?"
Terry Pratchett