I’m also having a problem downgrading to v5.1.3. The downgrade does happen, but if I try run v5.1.3 it says “error while loading shared libraries: libalkimia5.so.8: cannot open shared object file: No such file or directory” but Manjaro is not allowing me to downgrade alkimia at all. So I am stuck.
In my case, the latest update to KMyMoney v.5.2.0 has somehow reset the decimal separator to a comma, despite the main OS being set to a decimal point. But that is not the worst issue. Every time I type in any value like 581.14 KMyMoney converts it to 58114,00 and if I type in 581,14 it converts it to 58,11 so I just cannot enter any value right now. Which is why right now, I also need to get back to an older version.