deriv SD cv (87) ashtadhyayi.com hei.de L 87 ETT STT a 1.1.67 ALPH OLDHOMEPAGE NEWHOMEPAGE
The fifth case in a sUtra may mean "after it".
Example. Rule !!AdguNaH literally says "replace with /guNa from a अ A आ", but it actually means "replace with /guNa after a अ A आ".
Your translation seems to have nothing to do with the original.
The literal translation of the sUtra is:
tasmAd iti तस्मादिति "a from-it in a sUtra"
uttarasya उत्तरस्य "replaces what is after it".
As for instance, in AdguNaH, the from-it is At आत् "from a अ or A आ", and the uttara उत्तर "latter" is the /ik that is after a अ or A आ. So our tasmAdityuttarasya तस्मादित्युत्तरस्य sUtra teaches that we must understand AdguNaH to mean that the /ik is replaced with /guNa.
I didn't understand a word of what you just said.
Then look at candravasu's translation of this sUtra, it will maybe sound clearer.
tasminn iti nirdiSTe... < | 11067 tasmAd ity uttarasya | >> aN;udit savarNasya c... |
udas sthAstambhoH pU... <<< | L 87 | >>> AdeH parasya |