Hi Larry! I'm not quite sure what you mean here. If you have a computer font that is used in Windows and Linux, and you use that font to create a diary or journal (or any document)... then saving the file should store your document in that font. If the file is moved to another computer that doesn't have your special font, then I'm unsure what the result would be when opening the file.... but it will have to choose some font that is built into that system (and it may map back to English if it doesn't know what to do). I don't think there is a way to "lock" your glyph alphabet into the file if you type the file with a computer. Or if there is a way that seems to do that, then I don't think I would really trust it... computers are just too good at translating things when asked.
You could create your documents in your glyph alphabet on paper... then scan them for computer storage. That achieves your goal, as I understand it. But I don't think that is what you want to do here.
If you want to preserve your privacy, I think you should use encryption on your documents instead. And if you want to preserve your documents, you should also keep backups to external media, like flash drives, external hard drives, or DVD's. To me, encryption is a somewhat fragile thing... a small hiccup on your computer (especially when the file is open)... and you may damage the file so that it would no longer be usable. I say this because I lost an encrypted password database awhile back, and I was not happy to rebuild all the data manually after the corruption. Backups are essential for anything important to you
Cheers