I use a modification of the file preamble.at to exclude the initial set from achievements. The file is shared in the thread https://webwork.maa.org/moodle/mod/forum/discuss.php?d=4209

Anyway,
the problems skipped in the initial set still count into achievements like "complete_10_problems ", since the variable
$globalData->{'completeProblems'} is incremented for EACH solved
problem, even for problems excluded by preamble.at. For this reason, students may get "you solved 10 problems"
together with "you solved your first problem."

Any
idea how to resolve this issue? The initial set and the other sets are
opened simultaneously. Is there any information how many problems the
user solved in the first set? This should be subtracted from the
$globalData variable.

Thank you.