Marcie,
I do feel your pain. Been there, done that. Since Ancestry and FamilySearch have their own indices, search parameters that work on one sometimes don't work on the other. I've also found that FamilySearch sometimes just doesn't display a census match even if your search parameters exactly match what's in their index. However, IF you've found the census page on Ancestry, you can usually just browse to it on FamilySearch. Here's the method I use:
1. Let's say that you've found Lorenzo's 1870 census entry at https://www.ancestry.com/interactive/7163/4275083_00113?pid=40468254.
2. You can just Google something like "FamilySearch 1870 census" or bookmark the FamilySearch census records for quick access; link.
3. Click the link for the 1870 census. You can try a quick search on the 1870 census page which often works when a general search does not.
4. Otherwise, the next step is to scroll to the bottom of the search page where you'll see a link for Browse through 1,049,047 images. Click that link (fear not).
5. Refer back to the census entry on Ancestry.com and note the exact location. On the FamilySearch page, you'll select New Mexico Territory, then Mora, then La Cueba.
6. You'll then see the census images for that location. From the Ancestry page, find the image # and enter that; in this case, 3 (of 16). Sometimes the page will be one earlier or later.
7. That should take you to the exact same census entry on FamilySearch as on Ancestry. At the bottom of the page, under Image Index, you can scroll to the indexed entry. In this case, you can see the problem. He was indexed as "Sorenzo Romero". If you hover over his name, an icon will appear to the left that you can click to go to the indexed information.
I might have made it seem harder than it is. It gets easier after a little practice. It still does take a couple of minutes. You can get a little of that time back by using the supplied FamilySearch citation versus converting the convoluted format that Ancestry provides that doesn't include a hyperlink.
I personally do spend the time to find FamilySearch census entries that were originally located on Ancestry so that others can find it easily and freely. However, there is no expectation or requirement that you do so. Thank you for being conscientious about it.