There are many embassies that accept Wise and yes there are some who don't . No need to tell people to p off ...especially when they have not been rude to you.
Japan , especially Tokyo is strict in approving DTVs as the threads show.. Many rejected in Japan are successful second time around elsewhere Laos, Vietnam etc.
Dependents are often approved quicker than the main applicant but it is a busy season now for embassies. Anticipate around 10 business days. Yes, a letter outlining willingness to sponsor is required along with bank/finance details.