Holy cow, batman!
Thanks for the report. Don't know how it went this far, and hope you didn't waste too much time on figuring this out. It was -urk- a typo in the integer and floating point p-code interpreters. Text was fine.
A build with a fix for this is at ftp://ftp.ieinc2.com/pub/surfer/t1_3_27H.zip.
You unzip to \screensurfer\bin, replacing ielua.exe and adding the new program database file, ss13.pdb.
If you use it, you also need the file ftp://ftp.ieinc2.com/pub/surfer/menu13.gif, which you download to \screensurfer\hostserver\img.
You don't necessarily need this build, but it is the "latest and greatest" and worth testing with your application.