Yes, I'm a consultant at a Family History Center. I know what LDS means. You still haven't answered the questions. Perhaps you don't have any idea what records you're looking at.

LDS records are records of the Mormon Church - the IGI, Ancestral File, temple ordinance records, and other church records. Films of original records, indexes created by extraction projects, and the FHL catalog are not *LDS* records - they're not *church* records. They're simply records filmed or housed by the Family History Library or by FamilySearch.

LDS is a church.
FHL is a library sponsored by the church.
FamilySearch is a website sponsored by the church.
The FamilySearch website has both indexes and images, which are different things.
The Family History Library lends microfilms of original and derivative records, images or indexes of which may or may not appear on the FamilySearch website.
When you refer to them all with the same term, it's impossible to figure out what you're talking about.

"Recently I found my 2nd great-grandfathers, Jakob Grunewald's, birth, death and marriage records."
Where did you find this record? On a film? If so, which film? In a FamilySearch online collection? If so, which collection?

"I looked on the LDS website and they have no death records for Sippersfeld."
Where did you look? In the FamilySearch online historical records collections? In the FHL catalog? If in the catalog, did you use the old FamilySearch website or the new one? (It matters.)

"Again the LDS website doesn't have birth records for Münchweiler"
Again where did you look? In the FamilySearch online historical records collections? In the FHL catalog? If in the catalog, did you use the old FamilySearch website or the new one?

"Again the LDS website doesn't have birth records for Münchweiler and is unclear on which Münchweiler is which, as there are several of them. I assume I'm looking for Münchweiler an der Alsenz, as it's near Sippersfeld."
Münchweiler an der Alsenz is a reasonable assumption as it's the Münchweiler closest to Sippersfeld. The Family History Library catalog (not "LDS website") clearly distinguishes the different Münchweilers by identifying the Bezirksamt (district office) of each. Your task is to figure out in which Bezirk (district) Münchweiler an der Alsenz was located in the 19th century. (I'm just guessing on the date, since you didn't specify any time period.) You can use the Gemeindeverzeichnis Deutschland 1900 (Municipality Index of Germany, 1900):
http://www.gemeindeverzeichnis.de/gem1900/gem1900.htm?gem190...

"If not, does anyone have suggestions on how I can track down these records?"
The FHL catalog shows records for Münchweiler an der Alsenz, Sippersfeld, and Winnweiler.


BTW, this is the LDS website:
http://lds.org/?lang=eng