Yikes, I'm sorry to hear about your leaking cartridge experience, and will get this fixed for you right away!
After reviewing your order history, I see you purchased the 350ml internal bag cartridges a year ago.
Yes, it sounds like the VLM ink bag leaked, causing ink to flow out the air inlet point, and thru the air pressure tubes, which is how VLM ink got on the air inlet points of other carts on that side. Don't worry- it didn't contaminate ink in the other carts, and since there's just a small amount of ink on the other cartridge air inlet points (based on what you wrote, it sounds like there's magenta coloring on the air point, but not ink inside the body of the other carts- correct?), it sounds like it wasn't a large volume of ink, so won't cause problems with your printer or other carts.
We will send you a replacement VLM cartridge right away, and can offer you a discount if you would like to upgrade to our latest cartridge model, which is also 350ml size, but doesn't have an internal ink bag. Although we haven't had many issues with the old internal bag carts leaking (especially not with carts that have been working well for a while), we prefer the new cartridge design and feel they work very well. I will talk with Wells in the morning, and discuss the discount I offered, so he's aware if you decide to upgrade the whole set of carts.
Please let me know if you have questions or there's anything else I can help you with.
Best regards~ Dana