Changing Static Strings

Hello

I tried to install the plugin because of the Cost calculator plugin, using this documentation: https://docs.stylemixthemes.com/f-a-q/how-to-translate-or-change-the-strings-of-the-theme-and-plugins

It seems to be working back-end, but not front-end. Can you help me figure out why:

see back-end

versus front-end

Thanks in advance.

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