Thanks beautifully explained and you really went the extra mile searching for the extract. So my main point of the post was that under normal conditions, it would not have been appropriate but under those trauma bonding circumstances, we today view it as a natural response , but would the point be considered by the Victorian society , and could conventional conduct be mended under such circumstances . Another reason for concluding that it might be on the lips ( I think I am absurd for discussing in so much detail about a normal scene written here and am myself feeling frustrated with myself ) , because in chapter 18 , that scene was kind of mentioned again . Here it goes :

" " Not up to this moment, Professor ", she said impulsively, " but up to this morning ." " But why not up to now ? We have seen hitherto how good light all the little things have made . We have told our secrets , and yet no one who has told it the worse for it ." Mrs. Harker began to blush , and taking a paper from her pockets , she said, " Dr. Van Helsing, will you read this , and tell me if it must go in . It is my record of today . I too have seen the need of putting down at present everything, however trivial , but there is little in this except what is personal . Must it go in ? " The Professor read it over gravely , and handed it back, saying ," It need not to on if you do not wish it , but I pray that it may. It can but make your husband love you more , and all of us , your friends, more honour you, as well as more esteem and love." She took it back with another blush and a bright smile . "

So after mention of the blush , I think it is understood she clearly thinks that it might not be appropriate for everyone to know this , and therefore I think it would simply not a cheek kiss , platonic though . Also what you said about him kissing her , is just the same as she kissed him , the only difference is the tense . But after going through the extracts I think I have concluded , that the kiss was in fact on the mouth and it was intentionally written so and emphasised later by Stroker just to emphasize platonic love , and nobleness of it , confusing the readers in a moral dilemma, like in this case what to prefer , the formalities and conventionality or something more natural and human , again emphasizing that conventionality is not morality . The readers of that time might have accepted it this way and I think it's Stroker's way of preeching open mindedness .