Created attachment 127813 [details]
Discover's Korean screenshot, where accelerator keys are misallocated

SUMMARY

While this bug do not exist in QWidgets based applications, but Kirigami based applications seems to have the accelerator bug. Attached here is configuration dialog of Dolphin and update dialog of Discover, using QWidgets and Kirigami respectively. In Dolphin's dialog, only the translated message of "Switch between split views panes with tab key" has its accelerator key assigned, as only that item of the configuration dialog has alphabet. All other texts are using 100% Hangul, so no accelerator keys were added. That actually hurts usability (no accelerator keys available for Korean users) but I think this should be discussed in another bug.

On the other hand, in Discover's update dialog, accelerator keys are allocated to composed Hangul which could not be used as an accelerator key. Only the translated message of "Plasma Addons" has alphabets in this case. All others are using 100% Hangul, but accelerator keys are nevertheless allocated. This is clearly a bug.

Note that I checked the behavior of KHangMan's settings dialog which is using Qt Quick but not Kirigami, and the said accelerator key problem is not present there.

STEPS TO REPRODUCE
1. Launch any app using Kirigami and translated into Korean with LANG=ko_KR.UTF-8
2. Press Alt key to see the accelerator key

OBSERVED RESULT

When pressing Alt key, there is also underlines in Hangul characters. This is unacceptable as there is basically no way to press such accelerator key. Also in case of Plasma Discovery, there are shortcut keys with Hangul such as "Alt+설" displayed, but there is basically no way to press short cut key either.

EXPECTED RESULT

No Hangul characters should be underlined and used as an accelerator key. Usually translations will specifiy the accelerators separate from the main text. Kirigami should pick up accelerators only from [A-Za-z].

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kubuntu 20.04
(available in About System)
KDE Plasma Version: 5.18.4
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8