chore: improve readability of verification logic

[Ryun1]

List of changes

• Changed variable naming for signature verification on backend
• add a couple comments to improve readability

Checklist

• related issue
• My changes generate no new warnings
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the changelog
• I have added tests that prove my fix is effective or that my feature works

[github-actions]

✅ All checks succeeded

[Ryun1]

don't merge, let me check it
i havent got it setup locally yet

[vpaunovic]

This PR can be closed because naming change was included in some of previous PR's.