I booked a SQ + UA ticket using AC miles, India > Singapore > Australia > US. I just noticed the first name on the ticket is showing the initial of the 2nd word. Eg: For first name, passport - Rachel Karen, ticket - Rachel K.
All other information is correct. I have no idea how this happened. Must have been auto-fill mess up because my AC account profile doesn't have the second word or initial at all.
I noticed this while trying to add my Krisflyer number into the ticket for free wifi and it said name doesn't match account.

SQ chat agent says - For this, since your name arrangement on the passport is Rachel Karen Green, and we cannot guarantee if you can take the flight as we will base on what on the passport. For this, since you book this thru Air Canada, what we can suggest is to contact the Air Canada if what possible option they do on the ticket.

My understanding of the situation is that AC needs to reissue a ticket when partners are involved, needs current availability and they may even charge a change fee for it.

How big of a problem is this? Do SQ check-in agents have tools to fix this or will they actually create fuss about it? I never had problems with this in domestic US flights. I feel like this mostly depends on check-in agent but want to get a sense from others. I did a bit of research in FT and most of the threads were about "middle name" which is not the same in my case since its part of first name.