Reddit mentions of Franken Franken 1

The Frankenjura is in the unusual situation of having three more or less up to date definitive guidebooks:

Schwertner 1 & 2

Thum

Röker 1 & 2

They're all good, and like anything else in climbing/humanity/life, people tend to have tribal loyalties to one or the other of them. Schwertner seems to be the most widely read; I go for a slightly contrarian look by preferring Röker.

If you can't read German (well) then Röker is your best option because it has bilingual text. Schwertner also has a pleasantly cheap English language selected climbs version, but as the title suggests it's aimed above your grade range.

Frankenjura Extreme

This list of one guy's favourite routes, complete with snarky comments about insider Frankenjura climbing politics, is quite useful for getting an overview of where the good sectors are in various grade ranges:

Frankenura Top 391

Can't help you with Saxony, never been there.