Shar wants me to do evil acts.
No, Shar wants you to do particular things that she is interested in, whether those things are good or evil is subjective.
You can only believe that by ignoring pages and pages of D&D lore:
https://forgottenrealms.fandom.com/wiki/SharShar wants to return the world to nothing. She seeks the destruction of all life.
This is what clerics of Shar should do:
https://forgottenrealms.fandom.com/wiki/Church_of_SharRandom murders, destroying good institutions, generating mistrust among allies.
And of course alignment should open up and close off certain conversation threads.
You can't accommodate for all the logic any individual could follow, why would you reduce roleplay value based on your arbitrary interpritation of someones motives?
2) Save the tieflings [ Evil ] ( I think tieflings are evil Devil spawns and I want to watch the world burn. )
3) Kill the tieflings [ Good ] ( I think tieflings are evil Devil spawns and I will rid the world of them. )
Guess if you had used intelligence as a dump stat and were unable to make anything from the conversations I could buy that. But if you had a detect evil spell would clear it up instantly and any of your companions should correct your interpretation. In D&D evil isn't arbitrary, it part of you, you can detect it will spells, certain magic items will only respond to certain alignments.
For me you action have no moral consequences it reduces roleplay value.
"Hail there!"
"Oh, I know you, you're the one who slaughtered all those children in the Grove of Silvanus and then had sex with an evil cleric on an unholy altar"
"Well, not all were slaughtered I sold a few kids to the zent slavers and made tidy profit"
"right, right"
"Look, I'm about to go defeat the shadow lord who has been transforming your village into zombies. I may just loot his corpse or I may take his place and become the new terror in your life. Anyway, I wanted to borrow your Sword of Goodness and Light so I defeat him"
"Well I don't see why not. Oh and rest assured we will take up collection for you even if you do end being worse the shadow lord"
"Ta then!"
"Ta!"