changes language error message automatic to other language

Hi guys,

I have allot or contact forms on my website (around 20). All the error messages are in English. i would like to change them in dutch. Is there a way without changing each contact manually error messages? With making new forms there is no problem but the old contact forms error messages are still in english.

Thx for the help

https://www.ads-software.com/plugins/contact-form-7/