I ran into the same problem and when I check my variables in Season 1, the variable in question "
c1_e1_d5_miranda_dm_answer4" was set to False and in the values_s1.rpy in Season 2, which is doing the import, it is defaulted to False.
You can get past the error by editing values_s1.rpy and deleting line 2153.
To answer your question on other variables being broken, in values_s1.rpy there are only 3 variables assigned after this, which is the MC name, surname and nickname, so I don't think they will get assigned correctly if you ignore the error.
I just deleted the line mentioned above and then restarted the game and it imported my save fine and shows the correct name for the MC that I used in Season 1.
Hope that helps.