wanted to ask if you could also make i18n adjustments via config.yaml without editing the PHP file?
Well, actually it is possible if you create a language file that returns the config data. But why do you need it that way? Just use language files and keep your config file clean.
and add your i18n strings to config/config.yaml. Be careful with unquoted strings if you use colons etc.
"Search for anything...": "Suche nach irgendetwas..."