I am glad that you are spending time digging into this issue.
Here are the correct interpretations that I believe are consistent with ANY reference in the Tipitaka:
1. Nicca means the view/perception that something/anything in the world can be maintained to one’s satisfaction and can bring benefits.
– Icca is the craving for worldly things based on the above perceived “nicca nature.”
– Anicca is the opposite of nicca.
2. The words with the additional letter “h” (niccha, iccha, aniccha) emphasizes those characteristics.
Now, if anyone can find contrary evidence to the above, we can discuss them.
3. Conversely, many English translations ALMOST ALWAYS translate “anicca” as “impermanence.” That is wrong.
– They sometimes correctly translate “iccha/niccha/aniccha” (as in #2 above). An example of the correct translation is the first verse that you referenced.
4. An example of an incorrect translation is in the second verse that you referenced:
“Sukhajīvino pure āsuṁ, bhikkhū gotamasāvakā;
Anicchā piṇḍamesanā, anicchā sayanāsanaṁ;
Loke aniccataṁ ñatvā, dukkhassantaṁ akaṁsu te.”
Translated in “Jantu sutta (SN 2.25)“:
“The mendicants used to live happily, as disciples of Gotama,
Desireless they sought alms; desireless they used their lodgings.
Knowing that the world was impermanent, they made an end of suffering.”
Here, the translator INCORRECTLY translated “anicca” as “impermanent.”
– That does not flow with the rest of the verse/sutta.
If you repeat this exercise, you will find more inconsistencies.