If it cannot be sold, it cannot be sold. In that case, the walkthrough is mistaken. Don't worry about unsellable items, just drop them. (Unless they are needed for a quest, of course.) You can get more than enough money.
Some stuff can be sold in the main world, but I don't know if it works for items in the expansion. Even if yes, it's something which is very much just an extra, without any consequences for the expansion.
I've uploaded an update with ropes added to two barrels (one in the harbor, one in the monaster). It might take a while before it becomes available, but blame Apple for that.
The description wasn't meant to be misleading. The expansion in it's original form has been out for a very long time on iOS and before we released it, it was playtested. No one ever complained until now. I added the ropes to be absolutely sure. (I just can't check easily, because there is no search function in the editor.)
Also, make sure you have been away from either the docks (where you started) or the monastery for more than a week (in game time), otherwise you'll not find the newly added items. Maybe the best would be to send me a save file and I can then add a rope for you.
(How to get to them:
viewtopic.php?f=3&t=4624, send it to
redshift@redshift.hu)