Having checking images it's obvious the NX/TX and CX designation is intended as a "zoning" measure but the ?X200 and ?X300 models are essentially the same case design throughout and as such these printers have the same trapdoor arrangement.
Going on previous designs it's a high likelihood that they also have a single waste tube so a Solo tube kit should work perfectly.
Obviously the problem is that there's no reset utility at present so any waste ink redirection at this point is a pro-active measure (although not entirely pointless).
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Printers: (Canon) MP500/830, MX700, iP4000/4200/4300/4500/5200, iX4000(A3) (Epson) C84/86, D88, CX6600, R285/800/1900 (HP) K550, K850, K5400, L7680