What can be the missing values of BOM components acccording to datasheet ? LoRa sx1272
If you break it down into sections it begins to make sense: -

So, for the antenna matching you pick the components recommended in the antenna data sheet. This will more than likely make the impedance looking into C19 from C15 (left to right) be 50 ohms but, the antenna data sheet will tell you these values or, you use some form of \$\pi\$ filter calculator like this: -

Then, for the twin elliptic filter the website linked hasn't got the page listed (yet) but, you can use these formulas: -

And not that in order to cascade two filters (as per the schematic) you make input and output impedances the same. Note also, that for this to be as effective as possible there will be a notch filter frequency for stage 1 and one for stage 2.
Then. depending on the specified output impedance of the SX1272, you design C9 and L3 to be series resonant at your operating frequency.
Solve it bit-by-bit is my advice; \$\pi\$ filters and elliptic filters are designed to be cascaded so there is very, very little maths to worry about. Then plug the circuit into your favourite simulation tool and check out the results. Job done.