Certainly true. OTOH, I wouldn't want to start talking about "attacker" and "defender" while at the same time explaining to the kids that we are not trying to have a competition and trying to avoid confrontation. (Sorry to sound like an aiki-bunny. I don't think a bunch of six- to twelve-year olds, mostly beginners, should learn Aikido starting from fighting.) I'd much rather talk about nage or shite and uke and explain one aspect at a time of what I use these terms as. Which terms would you suggest? "The guy doing the technique" and the "receiver"? (Actually, most of the time, I'm using "I" and the name of my training partner. Whatever.)
Oh, and I never bought into "first technique" etc. as a useful name, at least for beginners. While I understand enough Japanese to more or less hear ikkyo as the same thing, I'm (afaik) the only one in our dojo and just giving strange, yet pronouncable, names to the exercises seems to work rather well. Using the same ones as the rest of the aikido world does not seem such a bad idea, either.
"Thrower" and "Receiver" could work. But the point is not really "no Japanese", but rather judicious and idiomatic usage that facilitates the best understanding for the student. "Shite/nage", "uke", "ikkyo, etc." are aikido-specific terms which are useful to know and provide a connection to the Japanese roots of the art. They're the shibboleths and jargon of the worldwide aikido community.
A word like "shisei", OTOH, has a perfectly understandable and idiomatic non-Japanese counterpart in the language of any aikido practitioner. The word has no special aikido-specfic meaning in Japanese. The budo connotations noted by Dazzler above can be communicated just as easily in English using the word "posture" or "bearing".