PayPal and Stripe merchants require that the processor payment page is unique. This cannot be translated to other pages.

For payments to work in other languages you must exclude these 2 pages from translation.

How:

Use the Exclude URL feature (WordPress Dashboard > Weglot)

Add http://yourdomain.coml/stripe-processor/ in the list. Check that this url is exact permalink name of the page url created with the Page Template “Stripe Charge Page”

Repeat the same for PayPal processor page.

Add http://yourdomain.coml/paypal-processor/ in the list. Check that this url is exact permalink name of the page url created with the Page Template “PayPal Processor”

Related help

Help article about Stripe Setup
Help article about Paypal Setup