I too have been trying the new site and finding it difficult to find anything. Poor Steve Roud, who didn't really have any choice about what they did, has been hearing about it. But he may pass that on to the site designers.

FWIW: This is a very temporary workaround, and Steve Roud has expressed his disapproval of it (without offering an alternative), but if you want to look up the list of entries for a particular Roud number, this seems to work:

https://archives.vwml.org/search/all:single[folksong-broadside-books]/0_50/all/score_desc/extended-roudNo_s%3A[ROUD#]

(Where you fill in the Roud Number instead of [ROUD#].)

So, for instance, to find Roud #23, you would enter

https://archives.vwml.org/search/all:single[folksong-broadside-books]/0_50/all/score_desc/extended-roudNo_s%3A23

To find Roud #1000, you would enter

https://archives.vwml.org/search/all:single[folksong-broadside-books]/0_50/all/score_desc/extended-roudNo_s%3A1000

And so forth. (The boldface in the URL means nothing; it's just to show you the part that you need to change.)

THIS IS SUBJECT TO CHANGE WITHOUT NOTICE. :-) It's me digging into the site, and is unapproved. If it doesn't work, we're back to being stuck. :-)