@acer Thank you for the clear explanation. I am trying to follow all suggestions given in your reply.
Please bear with me a little longer. Could you send some examples of what you meant by "one or more flags, ..., etc.", please?
Although I have added more catchStrings to catch
catch "time expired", "does not exist", "invalid input":
some errors were not caught:
Error, (in PolynomialSystemSolvers:-PseudoResultant) at offset 3101 in `RootOf.m`, time expired
Error, (in SolveTools:-MakeSolutions) at offset 3 in `:-40706.m`, time expired
I guess that answers your question, that is, the error message upon time-out does not always begin with "time expired". How to deal with it?