The sentence "appreciate your understanding in this matter" is correct and usable in written English. You can use it in contexts where you are thanking someone for understanding a situation or complex issue. For example, "Thank you for taking the time to listen and understand my situation. I really appreciate your understanding in this matter.".
We apologize for this mistake and the inconvenience and appreciate your understanding in dis-regarding the e-mail.
"I appreciate your understanding as we get this fixed in time for Wednesday and Monday".
Thank you for your understanding in this matter.
Appreciating your guidance in this matter.
We appreciate your timely attention to this matter".
I appreciate your sharing this matter with me.
We appreciate your patience and diligence in this matter.
I love the desktop app, it’s always running on my Mac. Ludwig is the best English buddy, it answers my 100 queries per day and stays cool.
Cristina Valenza
Retail Lead Linguist @ Apple Inc.