I have my oldest tulpa for almost 9 years. About challenges... I think the biggest challenge is to be both open minded to other's experiences while keeping your rational thinking too.
The thing with telling people about it is, what are they supposed to do with that info? Fact is, if you're friends with someone IRL it's a system-to-system friendship because that's how separate people interact.
And as Rusty just mentioned an example of, you'll get a lot of people playing therapist.
seems to me that it’s the same sorta thing as telling someone you’re a furry
aside from the negative connotations, it’s just not something that people are accepting of