Hi Alex,
Two suggestions... First, print to file and compare the output Postscript file for both the working and non-working scenarios.
Second, try varying the font used for printing text format (printer object properties, tab 'Text Format', font option).
Great suggestions...I had actually ventured down that road last night hoping to sneak a peek at what the driver is actualy building in the print job itself. Specifically I was hoping to see the HQ1200 vs 1200 dpi resolution settings.
As it turned out, even a basic TXT file when using the PSPRINT driver produced a fairly large output job when printed @ 1200dpi, here is a quick comparison:
2-09-16 8:50p 9665 0 output_pscript_1200.txt
2-09-16 8:11p 568252 0 output_ps_1200.txt
2-09-16 8:17p 9343 0 output_ps_1200_nofont.txt
2-09-16 8:16p 9218 0 output_ps_300.txt
2-09-16 8:14p 9224 0 output_ps_600.txt
the output_ps* files are from your PSPRINT driver, whereas the single output_pscript_1200.txt file is from the IBM PSCRIPT driver. what I found strange is that at the lower resolutions the resulting text files did NOT embed fonts, whereas at the 1200dpi they did.
Finally, HQ1200 failed to print altogether where I would encounter a crash in the PSPRINT driver itself, here is the entry from my POPUPLOG.OS2 file:
=== START ===
G:\OS2\PMSPOOL.EXE
c000009b
163e0bdc
EAX=00000000 EBX=0000002c ECX=00000000 EDX=00000000
ESI=0283000c EDI=02771400
DS=0053 DSACC=f0f3 DSLIM=ffffffff
ES=0053 ESACC=f0f3 ESLIM=ffffffff
FS=150b FSACC=00f3 FSLIM=00000030
GS=0000 GSACC=**** GSLIM=********
CS:EIP=005b:163e0bdc CSACC=f0df CSLIM=ffffffff
SS:ESP=0053:02525bac SSACC=f0f3 SSLIM=ffffffff
EBP=02525c6c FLG=00010246
PSPRINT.DRV 0001:00040bdc
=== END ===
The good news (I suppose/hope...

) is that the crash was consistent between the PSCRIPT and PSPRINT drivers, here is the matching log for the PSCRIPT driver:
=== START ===
G:\OS2\PMSPOOL.EXE
c000009b
1657d46c
EAX=00000000 EBX=0000002c ECX=00000000 EDX=00000000
ESI=0285000c EDI=02791400
DS=0053 DSACC=f0f3 DSLIM=ffffffff
ES=0053 ESACC=f0f3 ESLIM=ffffffff
FS=150b FSACC=00f3 FSLIM=00000030
GS=0000 GSACC=**** GSLIM=********
CS:EIP=005b:1657d46c CSACC=f0df CSLIM=ffffffff
SS:ESP=0053:02565aac SSACC=f0f3 SSLIM=ffffffff
EBP=02565b6c FLG=00010246
PSCRIPT.DRV 0001:0002d46c
=== END ===
Both the crashes produced a SYS3184 error.
Any chance you can troubleshoot this? While printing from your AE editor I was actually getting a "divide by zero" error...but no log in POPUPLOG.OS2.