each such application can swap the decrypted file on local disk and in that moment I guess there is not any security as AxCrypt only takes care about its own temp files (if any).
Yes. This is why you should only use applications from trusted sources. Only use the Windows Photo Viewer if possible. If you’re writing documents only use Wordpad, Notepad or Microsoft Word.
If you’re running Windows (the operating system) then you’ve got to trust Microsoft anyway so it makes sense to only use Microsoft applications where possible.
Would you have some recomandation for example, how to completelly avoid such risk?
If you use a computer you can’t avoid this risk. Make sure you encrypt your whole hard disk for ultimate protection.
Like for example, by recomandation of any JPG file viewer which definitely doesn’t use any local temp files?
Almost all software uses temporary files.
Is there anything else which can be done against this problem?
Click the broom in AxCrypt if the option is available. This clears any temporary files.
Use an up-to-date antivirus software, encrypt your whole hard drive and use AxCrypt. Also make sure you keep Windows fully up-to-date as well.
Beyond that there’s nothing more you can do.