If I modify the english language translation in messages.ini is it overwritten on upgrade?

Development
1

Mautic 3.3.3

I’m thinking of modifying some of the labels and such to make it more meaningful to the intended audience. Can I just modify the existing messages.ini files that are in each ‘bundle/Transaltion/en_US’ folder? Will they be overwritten if I upgrade.

Or should I try to make a custom language file and then choose that from the language dropdown in the UI?

Thanks!