OK, so maybe this is a networking issue instead of an X11 problem. Let's try some simple things in tcsh. First, let's see if this problem is specific to that command or dataset by using the built-in sample surfaces and a simple prompt.

#A string identifying programs launched by this script
set PIF = DriveSumaTest
#Quiet previously launched programs
@Quiet_Talkers -pif $PIF

#Get a free line and tag programs from this script
set NPB = "-npb `afni -available_npb_quiet` -pif $PIF -echo_edu"

# start suma, let it load just it's own built-in surfaces
suma $NPB &

# give suma ample time to wake up (much more than should be needed)
sleep 5
DriveSuma $NPB -com pause "Testing suma"

Now repeat with the spec dataset and same command.

You should get a prompt appearing on the screen.

@Quiet_Talkers -pif $PIF
suma $NPB &
sleep 5
DriveSuma $NPB -com pause "Testing suma"