Hey Tovakwyrmstalker, thanks for the interest in the game. The A5 version is essentially the booklet sized images resized (i.e. shrunk and stretched) to fit the A5 format size. I was originally a little hesitant to produce this size as it is a bit of a pain trying to maintain multiple versions of multiple books so this was the compromise option.
I haven't personally printed the A5 size of the rules compendium (I have printed A5 copies of the individual books) but from uploading and looking at the document through Doxzoo it looks to me to be 'acceptable' (i.e. the image shown above doesn't cut-off the titles).
If you are printing through Doxzoo, you can use the A5 (cover included version) and select the 'Cover design is included' option if you are experiencing an issue with the pdf cover. The reason for the 'No Cover version' was to appease a few requests from people wanting to print through Lulu.
It seems like that trying to cater for people's individual preferences opens up more challenges so you may just have to work with the files you have.
However, someone on the HoA sub-reddit has produced an A5 version (link here).
Hope that helps a bit.