Since you haven't used AI for anything substantial, it will be difficult to get to a conclusion that it improved your personal development directly. However, if you are willing to be a bit flexible with your writing, I think you can tie your use of Grammarly to some indirect resulting personal developments. Off the top of my head, I can think of:
- By using it, you have saved significant amounts of time you would have normally spent reviewing and rephrasing your writing. This enabled you to invest more time and effort into improving your understanding of the subject matter of your coursework and into improving your understanding of the law firms you were applying to. The, you could give concrete examples of this and/or explain the outcomes: did your academic/professional interests change in any way? did you obtain better results - more success in application or better grades?
- By using it to assess your manner of writing, you have been able to notice patterns in the errors you make when writing. This has allowed you to enhance your attention to detail and also improve your understanding of your strengths and weaknesses in your ability to articulate your thoughts. Then, you can explain how this progressively led to you improving your capacity to use language precisely. This arguably does not only also betters your capacity to express yourself both verbally and in writing, it also improves your ability to minimize ambiguity in thought itself (as the very act of reasoning involved representing concepts in language). Granted, this point might be a bit of a stretch, but I don't think it's impossible to make it fit for an application form answer if you can illustrate it by using some practical examples.
The other point I wanted to mention is that the application question says 'AI
or other technologies'. As such, maybe you can think of some other new technology besides AI that you have used recently - perhaps some smarter search engine when looking for further resources in your research for the coursework?