Look, I hate Merkel much, much more then the next guy (literally worst German Chancellor since...) but that doesn't mean that she hasn't been trying to make the best of the refugee situation, unlike some leaders.
You think my judgement is based off of hate? No, I quite like Merkel. My judgement is based off of her deliberate exacerbation of two out of the three last crisis to hit Europe.
I will keep calling them refugees as long as people keep using the term immigrants as an excuse for inaction.
Of all the reasons to support inaction, semantics is none of them. Also that's not the debate to begin with, as the choice is not between open borders, border control and inaction. It is bizarre to call things that are not to things that are, by that same reference all shall continue calling everyone immigrants for as long as people keep using the term refugee as an excuse for inaction.
What course of action could Merkel have taken that would be an improvement on the current situation and avoided this problem in the first place?
You been lurking the Europol threads? Lots. Starting from when Merkel first shut down her own party's attempt to declare the Balkans safe and her failure to send sufficient aid and her terrible life choice to attack the first nation to actually enforce its border all the way down to her declaring all refugees were welcome all the whilst she had dismantled Europe's ability to sort migrants from militants from refugees? In 2014 it was no secret that the majority of migrants were not from Syria, because they were just a continuation of the Med boat human trafficking from 2012 onwards. She needed to justify immigration at a time when Germany was most opposed to immigration, so she just called people coming from around the world Syrian refugees with very, very predictable outcomes. At numerous times she's had the option to start damage control and has even gone on to tell the news she fears Germany has lost its social centre (of course she does not take responsibility for this, Germany just "lost" it and its coincidence that its a result of her leadership). It's a great big mess that will never be fixed because Merkel is either a dogmatist or a careerist, even now Germany's border control and deportation efforts have stopped or returned tens of thousands of migrants out of millions arriving yearly.
Honestly what couldn't she have done? She was inactive, simple as. If you expect millions and millions of people to arrive you either prepare to repel them or accommodate them, she did neither, stopped her subordinates doing the former and listened to finance ministers who did not live in reality for the latter. As a result she promised the Germans that refugees would pay for themselves and now has millions of people with no work skills relevant to a highly developed economy like Germany, so their tax base already strained by one demographic bomb now is strained by two.