Canadian artist Zen Rankin has published two encrypted messages he created in his youth days. Can a reader break them?

Siegfried Schwabl (born 1917) from the Salzburg area, Austria, wrote an encrypted diary. The solution is known, but has not been published. Can a reader decipher the diary excerpt that is available online?

Can a reader decipher this encrypted diary page I found on the internet? I don’t know by whom and when it was written, but I’m sure that it can be solved.

Today I am going to introduce two encrypted diaries. Only one of these is solved. Can a reader decipher the other one?

In the 1920s a woman named Grace Gull wrote a diary. For some text passages she used a secret code. Can a reader break it?