Walkthroughs for custom maps.

Only luck with random encounters is needed to complete it.

"The distribution" plays a role, but it's difficult to assess how big of a role it plays. As you progress, the artifacts that you didn't find earlier will eventually appear, and others – even in multiple copies.
I've attached my starting save; you can start with it if you're still interested in this map. Let's see your own; we can compare. Did you try to complete it once, or did you replay it? I can try to complete it again, but later: I've just started playing one of the old best maps that I hadn't read anything about before ("Vanadia SoD edition").
My luck (I also made detailed notes about my playthrough) was as follows: in the sea, near the drowning men, I found the Sword of Justice, the Tome of Earth Magic, and 2 parts of the Well of Magic (I bought the 3rd on the black market). What did you find?
In general, I'm a very "average" player – "pros" can probably complete this map 2-3 times faster.