As far as we can tell, the closest accent in modern English to Middle English is the Staffordshire accent, short vowels and not much colour.

Certain things still survive, for example in beekeeping, we talk of a colony being "queen-right" when the colony is producing spare queen cells ready to either swarm in the early summer or to replace a failing queen.

There are certain Germanic constructions you've missed, such as the use of a conditional subjunctive in the term "and" - it survives in the Flemish "en" nowadays, which also has a meaning of "if". Pulling the suggestions above together gives the following.

The story skips some bits. Mary asks Joseph at the start what the tree is: Joseph doesn't see anything odd about it, and says that in summer, it bears fruit to fill your boots (No mention of stomach ache!). That triggers a pregnancy craving in Mary, which Joseph won't answer (this being a time when fruit out of season wasn't likely, unless you had a rohmtopf available - and that much booze for a pregnant woman wasn't a good idea even then). He's got an idea she attributes the pregnancy to God, but he's not buying it: let whoever put the bun in your oven do it, he says - he's now got his back to the tree. Suddenly, the tree is in fruit, and even then he's not satisfied, the fruit's out of reach - the tree has to bend over for Mary to pick her own before he realises this is a miracle and the foetus' father is God. Sudden change of attitude...

22 Now let us wend our way forth, as fast as we can,
23 And may Almighty God speed us on our journey.

24 MARY: O my sweet husband can you tell me,
25 What is that tree standing upon yon hill?
26 JOSEPH In truth, Mary, it is called a cherry tree;
27 In summer you might eat your fill of it

28 MARY: Turn again, husband, and behold yon tree,
29 How it blooms so sweetly now.
30 JOSEPH: Come on Mary, let's get to that city,
31 Or else we may not be blamed, I tell you in earnest.

32 MARY: Now my spouse, please behold,
33 How the cherries are growing on yon tree.
34 I would dearly love to have some,
35 If it pleased you to labor so much for me.

36 JOSEPH To fulfill your desires I shall try, in security (faith?),
37 Oh! to pluck one of these berries, it's daring work
38 For the tree is so high, it will not be easy
39 Therefore let him pluck cherries, who fathered your child.

40 Now, dear Lord, I beg you, grant me this wish
41 To have some of these cherries, if it be your will
42 Now I thank God, this tree bows down to me!
43 I may now gather all, and eat my fill.

44 JOSEPH Oh! I understand! I have offended God in the Trinity
45 Speaking to my spouse these unkind words.
46 For now I am convinced it may not be otherwise,
47 But that my spouse must birth the King of Bliss's Son
48 He helped us now in our time of need.

OK, for a finished product I'd do another pass, getting rid of the anachronisms and tidying the ideation, but as it stands this halfway house shows how we get from there to wherever we take it.