For some elements (like buttons) the Modeler adds the English (US) and the Dutch captions when creating them. This happens whether or not you have those languages in your project. If you start in English and later add Dutch, you will find that a lot of buttons already have Dutch captions. Microflow buttons are not special; "New" buttons will already have "Nieuw" set as their Dutch caption. However, for microflow buttons the English and the Dutch texts are both "Microflow" which may be confusing.
Do you suggest that we do not add a Dutch caption for microflow buttons? Are you happy with 'New' buttons getting the caption 'Nieuw' by default?
Update: Removing captions in other languages when editing seems a bit drastic. If you change the caption from "New" to "New user" you probably do not want the English texts to be cleared. This would mean that the end user sees "New user" instead of "Nieuw".
I cannot think of a satisfactory solution right now. You can simply search for the word "microflow" in the batch translate dialog to find all suspicious texts.
For any button other than a microflow button it is really nice that they get a default translation.
I would like the following for all buttons: Buttons get a default caption as it works now, as soon as I change that caption, the caption in all other languages is removed so it works like any other caption.
I really like the default behavior of captions in Mendix because this helps me not to forget translations. Batch translate works great too. Just sort the target language text which makes all missing captions appear at the top of the list.