How do you do Guilin?

Actually, it is possible because beside Kuala Lumpur, you can also use Seoul (operated by Asiana) and Taipei (operated by EVA). Now, it depends if you can construct some logical and feasible itinerary... You can check if you can do that or maybe wait for restoration of flights to Hong Kong.

I don't think these routes are currently active, maybe in the past. Only KL right now.

These flights may gradually resume in the following days but now it seems that obtaining a Chinese visa in advance is more recommended.

Actually, Asiana resumes Guilin starting in late September and EVA Air is looking forward to changes on agreement from March of this year when mainland China and Taiwan have agreed to reinstate flights from Taiwan to 10 mainland cities. Guilin was not a part of the March package with the exception of charter flights. Hopefully, even the flights from Taiwan to Guilin will be restored soon because Guilin was and still is an irresistible magnet for Taiwanese visitors. Also, I apologize for not being precise in my first post (answer).

Although I was able to find a small story claiming this from earlier this year, Asiana offers no such flight as of yet. Perhaps not happening now.