Word stores the text language as part of the formatting, effectively, and it can change mid-sentence. Spell check wouldn't really work otherwise in multi-language documents. So you probably have to select everything once and set your preferred language.

It also gets quite clever with detecting repeated formatting. Just like Word can notice when the part up to a colon of each enumeration item is bold and does this automatically, it can notice that the second column of a table is always the same language and can even change the keyboard layout accordingly. But overriding the language once for everything should stop all that, still.

The most brain dead thing about Windows, IMO, is that the keyboard selection is tied to locale. You want UK English but using a US keyboard (as you do on a laptop)? Screw you, it’s US spelling or a UK layout.

Nothing is tied to anything on Windows in that respect. Contrary to how other systems handle this. On Windows you have locale/culture (how to format numbers, dates, etc.) separate from UI language (what language menus, buttons, etc. should appear in), separate from keyboard layout.

I just encounter countless broken programs that don't really support that distinction (e.g. Chrome ignoring date/time formatting settings in its UI since UI language and locale are being conflated, some applications trying to guess the UI language based on the locale or even the keyboard layout (what thought was behind that, I cannot even guess). It's a mess, but mostly on the application side and probably because lots of cross-platform applications don't even know there is a distinction on some platforms (and gettext not knowing about UI language and thus using locale doesn't help either).

I find the keyboard layout switching really awkward but for different reasons. On MacOS/Linux, setting the keyboard layout is global - under windows it's per-application and the default is for shift-backtick to switch between layouts which is something I manage to hit pretty frequently.

When I was working on a host where I needed two layouts (US-Dvorak + US-Qwerty for other users) I ended up solving the problem using AutoHotKey to hook all keys and send a different keyevent. It was pretty gross but it bypassed all the issues I was having in a convenient way.

Perhaps you could hook US symbols such as "$" and rebind to UK equivalents with AHK? Alternatively, creating a modified EN-US keyboard layout which has relevant key-symbols would also work / be less hacky, but probably require more effort.

It's been global by default since Windows 10, AFAIK (and comes with a better (well, a) UI for switching as well with Win+Space. I've since disabled all the other shortcuts, as I've been hitting Alt+Shift far too often.

Huh? I’m using a German keyboard with en-US Windows without problems.