tl;dr: When using multiple keyboard layouts, it's would be very useful if Edge would remember the last used layout for each tab. This would save us from having to alt+shift every time we change tabs.
In countries where the native script is not Latin, one finds oneself needing to use multiple keyboard layouts - one for Latin input and another for the native script input. Often, one works within multiple contexts wherein each context requires a different keyboard layout. e. g. a programmer will have one window open for coding (which requires an English layout) and one window for instant messaging (which will typically be in his native script).
It begins to become somewhat of pain to change keyboard layout each time one switches context. Operating systems recognize this and offer an option to localize the keyboard layout setting to the program in use, such that when switching programs the keyboard layout will switch automatically.
Nowadays, much of a users life may be spent inside the browser, seeing as so much can be done from within the browser, e.g. coding, messaging, document editing, shopping etc. etc.
It is common to need different keyboard layouts within different browsing contexts, e.g. coding and shopping may require an English layout whereas messaging and editing documents will typically require a users native language layout.
However, the OS level segregation of input settings per program will not be of use within the browser since at an OS level all tabs are recognized as one program.
It would therefore be a HUGE productivity enhancement if Edge would fill in this gap and maintain different input settings per tab.