If you want cuttlings to form roots in soil you need to make sure that there aren't many nutrients in it, otherwise the cuttling will get stunted by the salts and fall into a state of doing nothing and will be dead but won't wilt (if air is saturated with humidity). You won't get any nuteburns in this state because the cuttlings will refuse to take saltwater in.
If you have an EC meter you can control this by flushing the pre-fert soil with handwarm water and measuring the drain, flush until EC is 0.1 or less. Use only very soft tapwater or rainwater or RO water to flush and on cuttlings, some tapwater has an EC higher than 0.5.
Or you can use neutral medium like rockwool (press together under water if it refuses to take in water) where you won't encounter any rootshock and can control if the cut formed roots every 3 days by looking at the ball which can be stuffed into small liquor glasses which give them enough weight and prevents the wool loosing humidity too swiftly.
And if a cuttling refuses to root you can unplug it from the wool and check in on the cut to find out what's the problem:
- If the inner white material retreated and you see a hole then the medium wasn't damp enough: cut it away until the place looks fresh and go on.
- If the place looks brown and is perhaps slightly slimey then your medium was too wet which prevents oxygen from reaching the plant material which subsequently rots. This time you need cut more away from the stem just to make sure no early rot water is still present in the lower part of the plant.
Only take cuttlings from healthy plants still in grow phase preferably from the lower part of the mother but not ones that stretched too much because of insufficient light. The stem should also be of normal flexibility, look green and not of "woody" appearance.
If you want to cut down time until roots form by 50% bath the cuttling at the cut in an auxin-solution for 30s directly after the cut then put into the medium allowing the rest of the solution to be soaked into the medium. Spring is the perfect time to make this from new growth from weeping willows. Keep that stuff frozen in between uses.
Leafes will get yellow over time, perhaps the lower ones fall off. Refuse to feed it any nutes! You'll do more harm than good.
If anything only spray nutes on the leafes. Buy a professional product for this and don't overdue this if "it doesn't work" ( = yellow leaf will most likely stay yellow anyway...)
Once roots form wait until you see enough of them before releasing them into an environment with lower air humidity. If a freshly rooted cuttling only has some very small and basic roots and you place it into hardlight with harshly pre-fertilized soil it will die in a day.