I question whether a publisher is going to produce a book using a custom font. The complications of making sure such a book was formatted correctly on all possible digital devices don't seem worth the risk and expense. If they are willing to include them at all, I expect they will do so using a graphic.
And, as a generality, publishing is a business and every book proposal is evaluated on a cost benefit basis. Any additional production costs that your book requires factor into that decision, meaning that the expected benefit from publishing your book has to be that much greater for them to say yes. It is in your interest to make the cost of publishing your book as small as you possibly can. In other words, avoid the use of alternate fonts if you possibly can, and do them yourself if your can't avoid them.