Learn Turkish: Bana kalırsa bu karar yanlış. - If you ask me, this decision is wrong.

It literally translates to "if it remains to me" or "if it is left to me." It breaks down into bana (to me) and kalırsa, which is formed using the verb kalmak (to stay/remain), the aorist suffix -ır for general statements, and the conditional suffix -sa (if). It's a very common fixed phrase used just like "in my opinion" or "if you ask me."

Since this lesson is about expressing perspective with açısından, could I say benim açımdan here instead?

You could say Benim açımdan bu karar yanlış (From my perspective, this decision is wrong), but it sounds a bit formal or analytical. Bana kalırsa is much more natural and conversational for sharing a personal opinion. We tend to use açısından and bakımından more for objective categories (like "in terms of cost" or "from a legal perspective") rather than for personal thoughts.

Can I use this structure with other people, like ona kalırsa (if you ask him/her)?

Yes, absolutely! This is a flexible structure. You can say ona kalırsa (if you ask him/her / if it were up to him/her), size kalırsa (if it were up to you), or onlara kalırsa (if it were up to them) to introduce someone else's perspective, often implying a slight bias on their part.

Why is the word "is" implied here without a suffix on yanlış? Shouldn't it be yanlıştır?