I am finding some issues with the PDFs downloaded from https://archive.org when we associate it with Proofread extension in Wikisource.
For example, see this file at Archive.org https://archive.org/details/pazhancholmala_gundert_1845 This file can viewed properly and downloaded from Archive.org.
I downloaded this file and uploaded to Commons. https://commons.wikimedia.org/wiki/File:Pazhancholmala_Gundert_1845.pdf From Commons also if we download that file we can view it properly and can read it.
Now there are 2 issues with Commons/Proofread/Mediawiki
- Inside Commons itself (for example, https://commons.wikimedia.org/wiki/File:Pazhancholmala_Gundert_1845.pdf) you can see that you cannot view the pages from this file in higher resolution.
- When we create Index file in Wikisource (for example, https://ml.wikisource.org/wiki/Index:Pazhancholmala_Gundert_1845.pdf) and try to work on a page (for example, https://ml.wikisource.org/w/index.php?title=Page:Pazhancholmala_Gundert_1845.pdf/7&action=edit&redlink=1) you can see that nothing much can be seen on the scanned page.
The second issue might be the direct consequence of issue 1. Could you please look into this issue.
I suspect the issue is closely related to the PDF generation method at Archive.org. But I am not sure about that also since the PDF file as a whole is perfectly fine.