The problem with semi lactics is that they age very fast while blues take their time. For this you need to begin by modifying your recipe to age slower.
The second issue is that you are not wrapping the outside and all your growth is focused on the outside. It gives you an insane volume of blue and accelerated proteolysis which could cause the cheese to bitter up. You really want this to be a random thing that grows inside the cheese and not all over the outside. Additionally using veggie rennet may have contributed to the bitterness.
The other thing is, this looks like a tiny cheese. Form factor is important and you need a reasonable volume and seperation between one side of the rind to the opposite side, as well as sufficient surface total to allow the cheese some time before it is covered all over. Another aspect of that is that if you are using small cheese and drying it rapidly, it will shrink and the rind that was created originally will now be loose and wrinkly - which is what your photo has.
My suggestion is to do a larger volume cheese, use yeast, ultra-dry that curd and then break it down in a bowl. Toss the loose curd with the salt in the bowl and then simply and gently take pieces of curd and move place them in the mould. Don't push them or tighten them, just pile them up so lots of air can be trapped mechanically in between them (you can only do that with curds that has dried enough).
As soon as the blue growth seem to take over the outside, pierce the cheese and cover the rind with foil. Age it in cool temperature. The blue thrives in it and the curd will knot slowly -thus preventing the bitterness.