This extension will still need to take into account the crazy horizontal (and vertical) tables that editors seem to create. Currently it seems to truncate the rest of the results, just like regular browsers fail.
A reliable alternative is probably to either push them into an appendix at the bottom of the table with landscape enabled for it, or alternatively try (and probably fail sometimes) to render it as landscape within the article. A long term solution is to maybe add a tracking category to highlight these huge tables and have editors fix them, maybe "Category:Nutty tables".
Examples:
https://en.wikipedia.org/w/index.php?title=Periodic_table_(large_cells)&oldid=749013106 https://en.wikipedia.org/w/index.php?title=List_of_United_States_presidential_election_results_by_state&oldid=753848943