To change “Login” or “Register” button you have to install Loco translate plugin you can translate these words with loco translate plugin by translating “Theme” you can follow the Article for Loco translate plugin.
Here we are only showing “Login” button translation with loco translate plugin and “Login” word change with DHVC in Page, you can change same as “Register” button and word.
To change “Login” & “Register” word with DHVC
To change “Login” or “Register” words on Login page please go to pages > Edit the page “Login” or “Register” > Edit DHVC Custom Form > Here you can change these words as in attached image.
Hope this Article will help you.