Concerning Trump's tweet. There was a time when successful meant just that. Successful. And we could trust this meaning.
'Very' successful for me simpy adds doubt, that maybe it wasn't actually successful, or he doesn't really know, but he wants to get the first word in, and that this is political grandstanding.
And I wish he would abandon final usage of the cliche': "Thank you for your attention to this matter". This conventional phrase is used in advance, bureaucratically, when requesting a subordinate to do something that has not yet been properly addressed. It is not appropriate here, again undermining his message content.