2004 Kia Sorento EX 4x4 --- Radiator Fluid Lead

My wife's 2004 Kia Sorento had the radiator fluid reservoir replaced w/in the last 6 - 9
months after we saw a puddle of yellowish / green fluid on the garage floor.  Both our
mechanic and the Kia Dealership agreed that it was the reservoir that needed to be
replaced + the A/C assembly, but since our mechanic isn't a licensed Kia mechanic,
we went to the dealership with his recommendation.  Now, a few months later, we're
seeing a puddle on the floor again.

Could the replacement reservoir crack that easily and soon?  Or, is it possible that
there is a hose / grommet that is loose?  We need to get it fixed, not trying to get
around that, but I'd like to have a decent idea of what our mechanic or the Kia
Dealership may say when the get under the hood.  So far, neither have tried to take
advantage of us (had that happen before, elsewhere), but I'd like to have an idea of what
they're saying and not be 100% clueless about what they're telling me.

Any ideas that come to mind, I'm all ears.  Many thanks in advance for any tips, tricks
and thoughts about what may be plaguing the replacement unit.