How to get handwriting recognition to recognise diacritical marks?

I tried using Windows 10 (20H2) handwriting recognition to take notes for the first time today, and it was a disaster. I was typing in English, and my language was set to English (UK) and my keyboard to US International, but I needed to write some German place names. Unfortunately, no matter how hard I tried, I could not get it to recognise ü.

By contrast, when I use Gboard on my phone, it will usually recognise what I am writing even if it is not in the current input language. Certainly it performs better if, for instance when I am writing in French, the input language is set to French, but usually I can get it to recognise French even if the input language is set to English or Dutch. And in any case, changing input language in Gboard is a very quick and easy process.

Given that changing input language or switching to the onscreen keyboard is difficult when my laptop is in tablet mode and the physical keyboard is disabled, how can I make Windows handwriting recognition work well enough for multilingual input for it to be useful?

Thanks for the reply.

I did in the end get it to start recognising ü without installing German handwriting recognition, but then I tried é and I just couldn't get that working at all, even though I tried it in common French words and I already have French handwriting recognition installed. And now, coming to think of it ü also turn up in a few French words (such as aigüe​).

I've read elsewhere that Windows handwriting recognition just sucks, and that handwriting recognition in Windows 10 sucks more than handwriting recognition in Windows 8.1, which sucked more than handwriting recognition in Windows 7. Could this be the problem?