There is a known issue that in lightroom keywords are ordered alphabetically.
Also, adobe stock interface does not enable editing keywords for multiple images
I have a catalog in lightroom. Relevant keywords are already defined there.
Bridge or other tools are irrelevant - its already managed in lightroom (and lightroom is a powerful catalog management tool).
Ordering keywords for images one by one does not seem be be a reasonable option - its huge number of images.
Since the relevant keywords are defined, What will happen if I will leave the order as is (alphabetical)?
Will the image still be found by buyers? How important is the ordering?
This issue does not occur by other agencies.
The level of importance of adding your keywords by order of relevance cannot be emphasized enough. It is critical. Without doing so you are severely limiting your potential for sales.
I recommend using Bridge to add your stock metadata as it keeps your keywords in the order you have added them.
I already have a catalog in LR with stock metadata.
Its not possible to edit keywords order for multiple images in the submission page. Editing keywords one by one will be extremely time consuming.
It's worth the effort in my opinion.