Hello Your font contains wrong metadata. It isn't marked as monospaced, so PSPad doesn't it in font dialog. Contact font authors and let them fix it. If this font is designed as monospaced, this flag should be set in font files.
You can see it e.g. in FontForge (Element/Font info (Ctrl+Shift+F)), OS/2 - Panose - Proportion -- <https://forum.pspad.com/read.php?2,72468,72469> PSPad freeware editor https://www.pspad.com
