It seems like Komento Portuguese (Portugal) only translated 53%

This is why some of the section is not translated yet, this following is the Komento language constant, you can add these into your template override section.

[gist type="php"]
COM_KOMENT_POSTING_AS_GUEST="Posting comment as a guest. "
COM_KOMENT_LOGIN_LINK="<a href="_QQ_"%1s"_QQ_">Sign up</a> or <a href="_QQ_"%2s"_QQ_">login</a> to your account."
COM_KOMENTO_NO_COMMENTS_POSTED_YET="There are no comments posted here yet"
COM_KOMENTO_QUICK_LOGIN="Quick Login"
COM_KOMENTO_SIGN_UP="Sign Up"
COM_KOMENTO_COMMENTS_ADD_YOURS="Add yours"
[/gist]

You can refer this documentation how to add these translation into your site backend language override section.

https://stackideas.com/docs/komento/administrators/how-tos/how-to-create-language-string-override

Hope this will help.

Nope, it doesn't help.

I've created the overrides, changed the files en-GB.com_komento.ini and pt-PT.com_komento.ini and pt-PT.override.ini

Cleared cache, refreshed page.

But the text is still in English.

This is irritating... It seams the text has been hard coded without language tags...

it seems like it does translated, you can check my attached screenshot below.

But i realised this "Add Yours" we hardcoded into the php file, can you download my attached file and replace into this following file location and see how it goes?
JoomlaFolder/components/com_komento/themes/elegant/structure/default.php

Lastly, it seems like this 'quick login' language constant you haven't add yet.

COM_KOMENTO_QUICK_LOGIN="Quick Login"

I've managed to edit the pt-PT.com_komento.ini directly to translate.

I knew something had been hard-coded....

By the way, how about the "Posting as", what's the tag for this?