It seems that parser.y has several shift/reduce and reduce/reduce conflicts.

S/R conflicts are sometimes expected and/or acceptable, but I don't think this applies in this case. R/R conflicts, on the other hand, are almost never okay.

The current state of the grammar with all of the conflicts means that there are valid sentences, part of the intended-to-parse language, which will parse incorrectly or not at all because the grammar is ambiguous and does not reflect the proper language.

I suggest to get rid of all conflicts in parser.y and, above that, perhaps use the -cr goyacc flag to verify reducibility of all grammar productions.