Can I configure Swype to use two different languages for keyboard layout and spell checking? With my built-in iPhone keyboard that is easily possible, but I can't seem to find the setting on Swype.
Yes, that's possible in Swype. And in SwiftKey, too, by the way. Let me walk you through how I did it. But let me tell you why first.
For Stack Exchange, I use:

US English spelling, since we're on a US website. Though, as a European, I should advocate UK spelling. Then again, the UK doesn't seem to advocate being European.
A German keyboard layout, i.e. QWERTZ instead of QWERTY, because I've been using that layout for physical keyboards for the last couple of decades.

With the iPhone, it's easy to set those two differently. With third-party keyboards, not so much. But it is possible:
Swype
Preconditions: You have bought the app and performed basic configuration so that you can access Swype as a virtual keyboard in your apps.
Steps:

Open any app that can access the Swype keyboard.
Select Swype as input method.
Press and hold the space bar, then slide up to More Languages.
Do not click on any language! Instead, for the language you want to configure, e.g. &quot;English&quot; (the US variant is implied), click on the right arrow &gt;. It took me a while to discover this.
Choose the layout that you want, e.g. &quot;QWERTZ&quot; in my case. Voilà.

SwiftKey
Preconditions: You have downloaded the app and performed basic configuration so that you can access SwiftKey as a virtual keyboard in your apps.
Steps:

Open the SwiftKey app.
Go to Languages. Under Downloaded Languages, you should see at least &quot;English (US)&quot; and &quot;QWERTY&quot;
Click on switch layout for a language.
Choose the layout that you want, e.g. &quot;QWERTZ&quot; in my case. Voilà.


PS: I haven't quite made up my mind as to which of the two apps I actually prefer. I see immediate differences, but no killer criterion yet. I'll keep testing both for a while longer.