TC Bucephalandra can be quite sensitive and more prone to melt than emerse grown pots (and pots from a reputable aquarium nursery tend to be more stable than some sources which transplant plants from elsewhere into pots shortly before sale)
Sometimes Bucephalandra will (completely) melt in new setups so I’d add rare(ie expensive) Buce (or other plants) after tank is well established (3-6 months)
Java fern - as tank is small, choose a smaller variant
Moss - given your set up, choose any of the Tropica 1-2-Grow options (except T barbieri which quickly transitions to a lose amorphous blob unless rigorously controlled (and then any trimmed bits you’ve missed will take up residence e.v.e.r.y.w.h.e.r.e) - best management of this is grown on stones etc that can be easily removed for trimming)
Unless you want instant moss carpet appearance, one pot goes along ways
You can chop moss and jam bits into rock crevices, or sprinkle atop glue-on-wood (Jurijs mit JS style) or layer on wood, wrap with cotton etc line (recent Green Aqua Josh Sim aquarium scape video - the first shorter video, not the long workshop seminar one) ..... a very thin layer of moss that is strictly trimmed during the first weeks produces the moss result you will in ADA style scapes
S repens - read through the article on Tropica website, it’s not uncommon for emerse leaves to disappear slowly (or melt rapidly), just wait for new growth
Eleocharis acicularis 'mini' - this can be quite variable in growth (from slow to fast) so depending where you’re planting it, you could easily add 1-3 pots, unwrap the grass “mat” (as shown by Jurijs mit JS) and pinch into small sections and plant ~1cm apart
Once planted, older growth may obviously yellow and slowly disappear, or plant may continue looking green and just fill, either way it will form a carpet
What’s missing?
The rapid growing stem plant - look at
Tropica Auxilary plant list
H siamensis 53B or H zosterfolia or B caroliniana etc
I really like H micrathemoides as a fast growing small leaf stem plant - in my soft tap water it’s a dependable “easy” plant, though I find the 1-2-Grow version much less dependable than the pot
Rotala Vietnam H’ra is another small leaf stem plant that grows very easy in my soft water
Number of pots - much depends on your goals ... I prefer fewer pots and more room for plants to fill in, others want a scape that looks instantly full