SiampumpkinMost issues with this ink have less to do with the type/brand of pen being used and more to do with the size of the nib. Diamine recommends broader nibs for best results. What size nib do you have?
That being said, Kaweco sections, nibs, and feeds come apart easily if needed. So, if you find your pen getting clogged or otherwise struggling to handle the shimmer, you can easily take it apart to clean it.
SiampumpkinIn my experience Kaweco nuns do run a bit broader than other western brands (ex: Faber Castell). They‘re fairly wet writers, so you might be alright. The worst that can happen is that the ink doesn’t work, and you’ll need to use a different pen or get a broader nib for your current Kaweco.