Mimi,
>>>I find it quite difficult to translate because it searches only on translation texts, so when field is empty you cannot access it
Use yoursitename.com/admin/dev-tools/languages URL to search by text keys instead of translated text. For example following text key is not translated: {text key='base+base_sign_in_txt'} .
Go to the URL specified above, paste "base_sign_in_txt" keyword (remove the "{text key='" prefix and all other symbols like {}), check "in keys" check box and click search. This way even if the phrase is not translated, system will search by the text key and will give you the results.
In case with the "Welcome" section you showed in your screen shot. You will not be able to translate it using "Languages". To change the text of this section:
- log in as admin of the site
- open the page where "Welcome" widget is displayed
- click "Customize this page" ( located on top of the opened page)
- Near the "Welcome" text you will see "Settings" icon ( see screen shot attached)
- Click on that icon and translate the text in an opened window.
As you will notice, this particular phrase can be used only in one language. So once you change the text using above steps, text will be one and the same no matter which language user selects.