The action to switch to the "Smartcard management" still lacks an icon. In the old KDE icon theme Oxygen there was an icon ("secure-card"), but the new Breeze icon theme lacks this icon. I have requested an icon for this for the Breeze theme. See https://bugs.kde.org/show_bug.cgi?id=428278.

Hmm, interesting. I'm using the Back button all of the time to get back to the certificate list from the smartcard manager. Might be a Windows-only bug.

I suggest to also change the option to "Backup Secret Key..." (i.e. singular instead of plural) because the corresponding action does not support the export of multiple secret keys.

This doesn't help. I think that's because after

flush_cached_data (app, dobj->tag);

do_writecert does

do_readkey (...)

which fills the cache again.

Kleopatra does now support using multiple smartcards with multiple apps concurrently (at least as far as the backend scdaemon supports this). Only tested with master of everything so far.

I think you have missed the Key Pair Creation Wizard:

Create a personal X.509 key pair and certification request

kleopatra/src/newcertificatewizard/chooseprotocolpage.ui

I have added a workaround to Kleopatra: rKLEOPATRA57cf71b043d198f85270eb3b8782de6277b8b889

Still reproducible with current master of everything.

I had a quite old master of libgcrypt (probably from August 2). I'll update everything to master an retest.