Hey Mr. Numbers. You know they used to call me Mr. Numbers back in High School. It's actually a really dark story.
Tramadol lowers the seizures threshold. This means it makes it more likely, all things being equal, for you to have.a seizure.
Cocaine will further lower that threshold. I would never call it safe, but doing a line or two after using Tramadol shouldn't be lethal or serious.
What I fear is you losing control and using Tramadol and/or Cocaine pushing what you feel is "probably alright". We don't want you to have a seizure. This combination is dangerous by definition though, yes.