Complex sentence: Although she has some engineering skills, during the Crowd Ball event, she leaves maintenance of her CAD to Tatsuya but urges him not to alter the code, however during the event she notices an inexplicable improvement in her performance.
Split into simpler sentences: Although she has some engineering skills, during the Crowd Ball event, she leaves maintenance of her CAD to Tatsuya but urges him not to alter the code. However, during the event she notices an inexplicable improvement in her performance.