The FaitalPro small woofers certainly are over achievers and good value . I had a good result with the 3 inch variant in my recent Unsquare 3 way build and expect the same from the 4 inch. They are however still only a mid range / full range
and even in a line array will have no bass on their own.
For a design that certainly will work and probably with a
very simple Xover (200-300Hz), with drivers available locally,
at really modest cost I suggest the following 2 way (should be circa 93 dB ave) and be able to do 40Hz upward, ie true full range
mid / tweeter the Faital as Mich indicated
Bass one of the Hybrid 15H 15 inch drivers , eg
https://www.soundselect.co.za/hybrid-15h300-15-loose-speakerThe box will need a good size baffle to get close (in smooth response) to the Faital factory specs for eg

Caveat : high efficiency bass needs volume , so the cabs will be substantial.