Hope so for Dario.  [ They checked him.  The vet for your dogs?  Not a Herp Vet ... ]   Visual inspection done or what test done ?  
Something did happen from the fall.  [[ "didn't have big injuries " ]] ???   Blood… yes nothing visible wrong / nothing big  to the eye.  Shell strong yes , not broken yes  but what’s going on internally ?    Relative to Dario's size that's like you falling from 1500 feet !  
Was any x rays taken and what kind ?   
How good a doctor can read them matters too.  A few offices the vet does all on his/her own no specialist in the office. 
I know some still use a  old film  style x ray machine that does not show soft tissue well , this saves them money.   Much better digital machines been around for some time and have a smaller footprint and offers much better / higher resolution than film x rays and cheaper for you.   They show soft tissue very well.   The fact spitting  blood  from the terminal velocity of the fall / 6 stories , to impact on plastic roof then from that to the first floor something very possible happened internally.  
Is your vet a “herpetologist” /  turtle specialist  or dog and cat vet ?  
Did a "radiology technician" take the x ray or the doctor ? 
Did a radiologist “read" the x ray and make a diagnosis  to the vet ?  
Or did the vet do all ... ?   
Lots of questions need answering still before the all clear .    
In my career I found turtles yes are hardy but hide things well , another doctor   ( Herp Vet that treats turtles)   for  diagnosis  with a digital x ray needs to be seen , if "no" to any answers to above ...
Here's a link for Herp's :  
http://www.anapsid.org/vets/