Thank you for all the help. I am still struggling to make a real word at 3D. It is possible [likely) that I have made an error.
I have -pli-es. There is one obvious word but that doesn’t fit with the cross clues.
Your letter pattern is correct. There are two possible words, both common words beginning with the same letter. In theory both will work with 16a, but one of them will cause an intractable problem with 15d. Go with the 'engineering' one.
Jarsseven - perhaps I can help. As Meursault explained at #62 the new word for 10d is "NorsEls". 10d includes the words liNE Gets which includes the necessary triplet.