Completely missed your reply here, I didn't set the temp folder, it's what it used automatically, I assume it was set by the program...
No prob , anyway it was more a hint to the Author of the program than anything else, I understand that you as a final user can do nothing or almost nothing about it.
Why in my day ...
we used simple, straightforward paths with no frills, spaces, dots, etc.
This has worked just fine for the last - say - 35 (thirtyfive) years.
Periodically, from time to time, a new kid (often very capable, smart and what not) arrives and believes that Windows has actually solved issues with:
1) Long paths
2) paths or filenames containing spaces
3) paths or filenames containing dots
4) whatever other limitation the good ol' DOS
And regularly - before or later - he/she is bitten by it.
A reknown program, JFYI, and nothwistanding that the Authors (Nuno and Peter) are brilliant, has been Winbuilder, no matter the ambitions with it, at the end of the day it was resolved that the only way to have it always work as intended was to make sure to use it from a "WinBuilder" folder in root of a volume. (mind you it normally worked just fine on any other path, still - from time to time - someone found out something not working)
The 8.3 naming convention (and NO spaces) is so intertwined in anything Windows that is much simpler to respect it than to implement the myriads of workarounds/fixes/provisions that are often needed to cover "all" cases .