st +i or e >$t

"My" rule doesnt work 100%. too:-(
There are several old words where , at begin of the word, the
"st" fallowed by -i- or -e- did not changed the -s- in -$-
All examples from DEX

with "ste"
stea( lat. stella)=star, stei(serbian stenje)=rock, stejar(bg.
steZer)=oak-tree,sterp(unknown eytm.) =unfruitful
4 words . one latin, one serbian, one bulgarian, one unknown
with "sti"
stih(sl.stihU)=religious verse, stinge(lat. stingere)=to
extinguish , stingher( unknown etym.)=without an equivalent,
ashamed, incommode , stinghie(unknown etym)= thin wood
board,stirigoaie(veratrum album/Veratrum nigrum)
4 words one slav, one latin, 2 unknown,
that is all.
I mention they are "literary words" and all of them can be
spoken with "$t" there beeing no dificulty for pronouncing
them with "$". But between "can" and "is", there is a long
way. Literary, these are all the old words which , having the
st fallowed by -i- or -e- , do not change s in "$".
Why? I have no ideea.. They are not many, but they are enough
to dont be an accident I guess...