Multilingual spell checking on Whatsapp Desktop is not working

I had the same issue with Spanish and English. I followed these instructions to change the language priority, putting Spanish over English, and the issue was resolved.

http://osxdaily.com/2011/08/21/set-language-priority-mac-os-x-lion-auto-correct/

Even two years later on MacOS 11.1 (Big Sur) I have the same issue. Mac OS spell checking for me is on 'Dutch' but Whatsapp keeps forcing spell checking to 'English'. Sloppy work by Facebook, more interested in collecting my data than delevering a proper user experience.

Grtz, Sander.

Let me propose a simple workaround that worked perfectly for me. Issue: my system language is US English and I want WhatsApp spellchecker in Portuguese.

I‘ve downloaded from https://github.com/brave/brave-browser/issues/1947 the Portuguese spellcheck dictionary: pt-BR-3-0.bdic.

In the folder C:\Users\username\AppData\Roaming\WhatsApp\Dictionaries is located the US English spellcheck dictionary: “en-US-8-0.bdic”. I’ve rename it to “en-US-8-0.org.bdic”. Then I copied the Portuguese dictionary to this folder and renamed it to “en-US-8-0.bdic”.

That is all. Hope can help some of you.

I continue to have this issue as well. I followed the instructions at the link shared by Guillermo, making Spanish (for me) the top language and English second, and it helped, but is not 100%.