Is there a way to use isearch (only search i think that works in pdf-tools)? to search for either of two words at the same time? It would search in the pdf for 'eval' or 'valid' and move forward in each occurrence of either word?
C-M-s to invoke
isearch-forward-regexp then type
aaa\|bbb, where aaa is your first word and bbb is your second.
Alternatives, just C-s to invoke
isearch, then press M-r to toggle to regex.