A friend of mine is an substitute Elementary teacher, I'm fairly sure he's trained in English, he gets words wrong all the time too.
I don't just get words wrong, I will often write a whole sentence, post it, and realise days later that it doesn't really say what I meant it to say. If I'm lucky, I will find a better way to explain what I meant. But its gotten me in many an argument because I phrased something badly.
Or my particular horror when I told someone when I worked at Plusnet that DSL gets worse in the winter because its cold and they rightly corrected me that actually it should work better due to less attenuation on the line. I knew what I meant (that it CAN work worse in the winter, but its more down to damp joints) but once you've said something stupid, you feel like an idiot and it gives a bad impression of customer support not knowing what they're talking about.
This is one of my long standing problems, I tend to over-explain things as its safer to assume someone doesn't understand and ins and outs, but it ends badly if you word it wrong.
A few months back I got accused of mansplaining something, though I did laugh that one off because it wasn't that I over-explained because they were female, I over-explained because I ALWAYS try ti second-guess what their next question is going to be. I don't pay any attention at all to what sex/gender/nationality the person asking is online unless its relevant to the discussion, which it wasn't..