QdL is valid in the whole of DE on that day (from 9.00 on mo-fr) but ONLY on NahVerkehr=R/S or RE trains=more stops, NOT the sleek white faster IC or ICE. Same-same for Landestickets like B-W: these are ALSO valid on all local bus-tram/metro etc in that land. F is in Hessen land and this also offers its own landesticket, but only for small groups and they are not that cheap. I kind of remember you travel with the family-but forgot details.

HIdden deep in the bowels of the giant bahn.com site are some maps that show to where exactly the Landestickets are valid-B-W to somewhere just above Mannheim ( probably indeed a stop on the hourly RE trains doing MH-F), but I have forgotten which one. Dr Google will probably give the answer in millisecs. And there is no need at all to prebook, so check the locally folders+maps that ly out in any station in B-W. Or check their site bwegt.de. The point is then: from that stop till F will be in the RMV local VERBUND area, and this means that tickets often can only be bought locally from machine-but for the whole trip incl also bustram till final stop. So you have to get out train-find machine-buy tickets-and thus wait for next train (maybe 30 mins, maybe 60). And I understand its pretty cold+snowy right now in DE (not here in tropical BKK). SOME Can also be bought via the DB-navigator app, which then of course you have to install etc.

This trip is in fact not that str8forward on these tickets, as S->MH usually then goes via KArlsruhe=takes more time, as direct trains are only as ICE.

On bahn.de or .com simply use the setting ´Nur Nahverkehr´ to see what it delivers in timings. Any money-conscious German knows that since a very long time. OR see if bahn.com will offer any reasonable SparPreise for tomorrow-if at all probably only at very early or very late trains.

Frankfurt(Main) is not a part of Baden-Würrtemberg (BW). You cannot use these BW-tickets on ICE and IC. All the rest of public transport you can use (from bus, tram, U-bahn, S-bahn, RE’s, IRE, RB’s, of all local companies in Baden-Württemberg...).

Same for the Quer-durchs-Land (Only RB, IRE, RE and S-Bahn - no local transport), but that you can use all over Germany (- I think?).

Use the transport planner of https://www.bahn.com/en and tick off “Local transport only” to find connections you can take with aforementioned tickets. For IC and ICE you need to buy proper tickets or use your interrail pass.