Interesting, I did not find the small original screws secure enough, but again: Different people, different perspectives.
Yes of course, there is a bit of burn-in time. Actually I did not hear more treble energy after the upgrade, so I have kept the same toe-in as I used before. Now with the new crossovers fully burned in I find the treble much more listenable. I still have some ‘’toe out’’ though, compared to the recommendation in the manual, otherwise I find them too bright.
The filters are not heavy as the inductors are relatively small. So I feel confident it will hold nicely with the standard screws (also in transport). Needless to say that longer screws would be better, and your implementation with the inserts is the best.
I put in one radiator, moved the filter against it, and then shifted it 1-2mm back and drilled the opposite side of the filter boards. Put the screws in, took the radiator out and moved it to the other side and repeated the process. It makes for a very easy installation, with the filter just clearing the radiators on all sides.
At first listening, it looked like the whole passive section gained about 3dB efficiency above 1kHz. Obviously, this is not the case and clearly a sign of break-in. Probably mostly for the cabling as the Ludic Silenos cables are notorious in this aspect in the first 10 hours.
I understand most have ordered the filters with cables attached. If not, take a look at the Ludic cables as they are interesting:

Silenos, pure copper with Carbon per meter - Ludic Audio manufacturer in Europe for Audio accessoires
So who’s the nut behind this wheel? Who designed it? In collaboration with Physis, Ludic designed an exceptional cable the Silenos. A pure copper cable as the main conductor with a Carbon inner part that has a structural effect on music which is not available with any other cable technology...

@MortenB : out of curiosity, at what setting is your 'bass knob'? I moved from 10 o'clock (during break-in new loudspeakers) to 12 o'clock. With the new filters I feel that 13:00hrs might be the preferred setting. Isn't this an interesting hobby?