Brush pen inks for fountain pens?

I love brush pen inks, they are so dark and affordable. For example, the Deli 500ml ink in the first image (got the image from JD) is only about 17 RMB or $2.3 on JD.

I've been wondering what would happen if I use such brush pen inks on fountain pens. Recently I decided to give it a try on my Jinhao X159, which is cheap enough that I don't mind throwing away. It seemed to work well so far. Plus, I also tried it on my Deli fountain-pen-syle-brush-pen (which uses an ink converter but has a brush pen head) and have written close to 100 Chinese characters without any issue so far.

What might be the long term effect? Will these pens get clogged or damaged in some way? Did anyone have previous experience?