Welcome to EYB upstill. The search box is there as a quick search - type in any word and it will find any occurence of it - we look first in the recipe name then in the ingredients list - so any recipe that has that ingredient in the recipe name will be listed first as it's more likely to be a major ingredient.
To get a more refined search you need to use the 'Only Show' filter on the right hand side. So in the example you gave you'd select Ingredients/Meat, Poultry & Game/Beef/Joints - then to get the cut you wanted you'd type 'silverside' in the search box. You can find out more on this at How to narrow down your seach using Only Show
We've tried to link ingredients together that are the same but have different names in different countries - for instance there is a meat called girello that is linked to pickled silverside - which is apparently the same thing. So if you search using one name it will find all other recipes that use the other - same with zucchini/courgette and eggplant/aubergine. We welcome all feedback from members around the world who can update us on any variations we've missed.
The filter list is the closest you can get to the complete list, which is over 9,500 ingredients. We felt we couldn't list all of these, it would be too hard to use, so we had a huge job of categorising all those ingredients into the ingredient headings.
I'm familiar with silverside - as I live in NZ, eaten it but never cooked it. I think it should be linked to corned beef - are you able to confirm?