Hi, so
can I use tailoring based on attributes in participants table (like name) in question texts, welcome messages etc. in similar way like in invitation email? Apparently not, because in invitation email "Hi,{FIRSTNAME}, {ATTRIBUTE_1} worked fine, but did not in the welcome message inside the survey sheet. How could I use the attributes of invited (non-anonymous) participants as source in tailoring texts? Maybe I have missed something when trying to learn using the EM, I would appreciate any help.

You can via EM.

However, you can't access the token attributes the way you are trying. Have a look in the manual, it is described somewhere, but it must be something like {TOKEN:FIRSTNAME} or something like that.

Here you can find how to do it:
manual.limesurvey.org/Expression_Manager_HowTos

It is hard to find from the manual, but I understood that it needs to be just like you wrote, {TOKEN:FIRSTNAME}, rigth?
Thank you.