I'm worried that Michael Brookes' comment on some being randomly generated is being taken out of context:
"Not really, some are randomly generated, but others have been specifically placed to be found."
https://forums.frontier.co.uk/showthread.php?t=195658&page=542&p=3371375#post3371375
Follow the trail to the previous posts:
"Unfortunately the article on galnet was written by a player so it still most likely is just lazy POI placement."
https://forums.frontier.co.uk/showthread.php?t=195658&page=542&p=3371268#post3371268
And that post:
"I'm really excited in the spread of probes far away from the human bubble -> the article in GalNet confirms that it's not a bug"
https://forums.frontier.co.uk/showthread.php?t=195658&page=542&p=3371248#post3371248
"The article" which is thought to be "lazy POI placement" which is clarified as "some are randomly generated, but others have been specifically placed to be found" is discussing the crashed nav beacons and their morse, not the barnacles.
Admittedly there is some mention of large barnacles in the same post but I'm following the trail of specific points that each person is replying to. So I'd be careful assuming barnacles can be found randomly, it could be that Michael Brookes was referring to the nav beacons with that reply.
I can't find the article on the nav beacons now, but I think the galnet site is missing some articles.