Hi and welcome to Beoworld,
I am sure you will be pleased with the sound of a BL18/19 combo.
However, with this kind of setup you will have to deal with several problems - and maybe you will have to live with more compromises, than you would wish for.
1: if you connect your sources to the preamp via optical you only get sound - to see a picture, you will have to run a HDMI from each device to the tv in addition.
Why not just connect the sources to the tv directly (the Pana has the 3 HDMI you need) - and run the (one) optical to your preferred preamp?
Would be much easier in terms of remote-controlling. (Of cource you will have to connect the turntable via RCA directly to the preamp.)
2: the Rotel, that you mention does not seem to have an optical output . But you don't really need that anyway - the analog line-outs will be fine.
A problem with the Rotel is, that it has no dedicated subwoofer output - and that you must be sure, that the connected devices can output the sound as PCM as the Rotel has no Dolby/DTS decoders built in.
Maybe you should look for a multichannel receiver with preouts instead!!
3: in order to connect the sound wirelessly to the input of the BS Essence, you will - in addition to the transmitter - need a WiSA receiver.
The Essence has no wireless (line-in) option built in!.
4: according to your drawing, you intend to connect the BL17/18 to the Essence. The Essence has two PL-outputs, and you can not connect the sub directly. The BL19 has (only) a dedicated sub-input - and no outputs to connect the BL18 to (pass-through).
You could (if you use a multichannel preamp with sub-out) use the transmitter1 solution for the direct connection of the BL17/18 - a very good solution indeed.
You could then (instead) connect the Essence (via PL to RCA adapter) as a source directly to the preamp. This - however - would mean fiddling with volumen control from the Essence wheel and from the preamp at the same time - not an elegant solution. You should know that the Essense is made as a standalone solution - and that it will work best that way.
Another solution might be choosing another sub (the BS2) in order to connect the BL18 directly to it. You would - in addition to the Transmitter1 - need a receiver for this.
I am aware that the above can be quite confusing. But the setup you wish for is (sorry for saying) confusing - nothing for everyday (and wife/girlfriend) managing - if it should be established.
Did you ever think of buying a B&O tv as your next B&O purchase?
A newer B&O tv is THE hub for all that you want - it has the (multichannel) preamp for sound built in, good speakers built in and wireless function (WiSA) for additional BeoLabs built in too.
You can connect all your devices to it directly, without being concerned of any loss in sound - and you have one remote control for all (even the ATV).
A BV11 - and the BL17 for a start - would make things much easier and would in most cases be sufficient for sound/soundquality. Leaving the BL18's out - for better days ;-(
Hope this helps!
So keep reading.
Maybe some other Beoworlder with similar 'problems' could give other - perhaps different - hints for you.
Edit! Pushing the post-button, i see that already other beoworlders are concerned too :-))
Using a BSys4 and your Pana as a display might be a solution to consider, but not the most elegant in terms of remote-controlling.
Please let us know how things work out.
MM