Thank you! Good to hear that simply using a larger needle worked fine for you. Then I think I'll do it that way, too!
I started my Wisp now, or actually I started two. I thought I'd try it first with a slightly thicker yarn to make myself familiar with the pattern. But then I was actually already on my fifth repeat when I switched over to the "actual" yarn... the pattern is really nice to knit! So I think I will finish the other one, too, for myself. But now I'm knitting the one for my mother first. Using the lace yarn is less awkward than I thought before, and I like the way it's coming out:
The colours are actually more intense in real life!