When you are trying to understand the records on FamilySearch, here are some ways to get more information.
Record Type articles in the FamilySearch Research Wiki
Searching the name of a country plus the term "genealogy" will get you to the top-level article on doing research for that country. In the right-hand sidebar, choose the type of record you need more information on, in this case, Civil Registration.
In the section Locating Records it says:
Hungary’s so-called “personality law” prohibits archives from
providing access to birth registers for 90 years, marriage registers
for 60 years, and death registers for 30 years.
FamilySearch Historical Records articles in the Wiki
Each collection of records on FamilySearch has a corresponding article about the records. The articles about vital records or civil registrations usually have a coverage table showing when record keeping began and when general compliance was reached. In the case of Hungary, the coverage table is in a separate wiki article, Hungary Civil Registration - FamilySearch Historical Records Coverage Table, showing the number of records online by county.
In the catalog description for each record set.
Viewing the catalog description for each record collection, and reading the film notes, will give you more information about the scope of each record set.
In the main Civil Registration article, we are given the rolling window for records that can be open:
- birth registers: closed for 90 years
- marriage registers: closed for 60 years
- death registers: closed for 30 years
Usuing 2020 as the latest complete year (as I write this answer) this means these records likely to be closed:
- births after 1930
- marriages after 1960
- deaths after 1990
These rules apply to the records available in archives. However, that doesn't take into account the date when FamilySearch filmed or otherwise acquired the images.
Of the three records on your wishlist, the only one not covered by the privacy restrictions is your grandfather's birth certificate from 1925.
Entries in the FamilySearch catalog are often standardized on the names in a particular gazetteer. When you do a place search for Hungary, then chose "Places Within Hungary", the catalog says:
Place names are taken from these gazetteers: Magyarország Helységnévtára, 1881. Film number 599564 item 2, 973041, Fiche number 6000840, Book number 943.9 E5d
Looking at the countrywide civil registration, the note in the catalog entry says:
Images of births to 1920, marriages to 1950, and deaths to 1980
reported to and recorded by civil registrars. Coverage varies by
locality. This collection is being published as images become
available. Please visit the wiki or browse the collection to determine
The dates here aren't consistent with what we saw in the Wiki. Looking at the records online by browse, choose Tolna and then Újdombovár.
Two waypoints are shown:
- Births, marriages, deaths (Születtek, házasultak, halottak) 1904-1913
- Deaths (Halottak) 1895-1903
The records of births only go to 1913. The collection ends before your target date of 1925.
You can also test the index for indexed FamilySearch collections by searching for your place name without any given names, to see how many records show up. However, keep in mind that FamilySearch has many records which are still browse-only.
For the records which have been indexed, searching via the main collection search page for marriages gives 1,605,917 results for the range 1945 - 1950. These search results reflect entries for all of the people indexed from the records, so it doen't mean there are 1,605,917 marriages, but we can see there are some records. However, from the coverage table and other clues, we can see that the collection is not likely to be complete.
Try looking for other records in Australia to see if you can find more clues. The article Tracing Immigrant Origins may be US-centric, but you can follow the same principles for finding records in Australia, using the Australia Record Finder.
Bear in mind that the top-level date ranges shown on FamilySearch, Ancestry, and other sites are guidelines, and you should not assume whatever is in the database will be complete for that date range. What records are available are likely to be different for each location, and there might be references to events in the records which are outside the date range of the big collection. (For example, in some parts of the US, people had to record marriages as part of a land transaction, so marriages can appear in court record books that are in a different time period than the marriage took place.) If your people have siblings, study the entire sibling set to get information about possible migrations and to narrow the time frame for when a couple got together.
Also, it may not be safe to assume a marriage happened before the birth of the first child in localities where the couple needed permission from the authorities before they could marry.