Re: How do you deal with.....
Alrighty then. You have already done the hard part and got the information you needed. Yup, sempai's cussing and judgement was indeed at and about you. Sorta.
Mary's spot on, sempai's behavior is about sempai. If sempai is doing something you find unsafe or cant train with, tell her. We all have different comfort levels and if she actually impinges upon yours, good self defense suggests squeaking about it. If you really dont think the convo would go well, talk to sensei about it. The word sensei means "I've been through this shit before and I am here to help you through it."
Now, if one of my sempai (and I have plenty) cusses at me about me and my performance, it is because they know I can hear the message in the profanity. That's because they know me pretty damn well. They know I appreciate the human connection, intensity, and honesty that is all wound up in "Damn, Krystal, you ok? Because the ukemi you just took was some fucked up bullshit. That shiho nage wouldn't move a fly. What the hell are you doing, smoking crack?" Even my sensei has straight up actually told me my aikido sucks. When it sucks. But I joined the dojo with a fully ripened vocabulary and it took everyone about 5 seconds to see that my blue language was just emphasis and decoration, accurate description, hardly ever personal. Freed them up to tell me the truth as they understand it. Helps my learning for them to speak my language.
Speaking of language, I am finding it odd that your sempai is cussing about you at you in their second language. That's a really risky move on sempai's part. It may be that she doesn't get that the nifty bad words she learned have more impact in your culture than in hers. She might not even know exactly what the words mean. She may think she's being cool and personable. You could pull off a sweet tenkan next time she cusses at you. Ask her how she'd say the same thing in her native language.