I’ll get in touch with you again when I know more clearly about that plan.
Could this part also be written/said as "klarer Bescheid über den Plan…? I finally figured out “klarer” modifies “Bescheid” but wondered why the prepositional phrase was between them.
The “klarer” is an adverb here and it modifies the verb “Bescheid wissen”
“Bescheid wissen” = know, have knowledge about
“klarer Bescheid wissen” = know more, see more clearly (fig.)
You might change the word order to
… wenn ich über den Plan klarer Bescheid weiß.
or
… wenn ich klarer Bescheid über den Plan weiß.
Personally, I must say that I do not like the expression at all, because it mixes two figures which do not fit.
It should be “klarer sehen” oder “besser Bescheid wissen”.
In English I would also either say “see more clearly” or simply “know more”.