The native version of the sentence above is as follows:

Here the adjective is marked for neuter gender agreement, which characteristically happens when there is no overt determiner. Neuter gender appears on the adjective as ZERO. This is exactly the attributive context in which the –t ending is found: when the determiner (the construction) triggers gender agreement on the adjective and the agreement is neuter singular.

In addition, the t-ending seems to be especially frequent in the case of the adjective litje ‘small’. It is found in an attributive construction governed by the indefinite determiner like the following:

This adjective is a special case, as we will see. It also shows up in a predicative construction like the following:

The antecedent is a neuter noun, as is clear from the context. However, Saterland Frisian does not otherwise exhibit adjectival agreement in a predicative context. The following examples make it clear that litjet ‘small’ can be generally used in a predicative construction, regardless of number and gender:

So the upshot seems to be that the form litjet ‘small, little’ can be generally used outside the attributive construction. It is also found in adverbial contexts:

However, it tends to be used only in constructions governing gender agreement for the neuter singular. Forms in –t, for other adjectives, have been around as early as the middle of the 20th century. It is for example found in Herman Jansen’s Lesebouk foar Seelterlound (1943-1965):

Nonetheless, epenlieket ‘openly’ differs from litjet ‘little’ elsewhere. In predicative use, the form litjet also appears, whereas epenlieket does not. Fort wrote that such interferences could be heard especially in Skäddel (German Scharrel), but nowadays they are quite common, see Fort (1990:189). Originally, there was a different form used both for neuter gender agreement and, generally, in predicative and adverbial function. This was the form littik. So the old paradigm was litje – littik, and this has been changed to: litje – litjet. What is special about this word littik ‘little’ is that the neuter gender agreement form is also used for predicative and adverbial use, much like the zero form of regular adjectives. In Ostfriesisch Low German, the form lüttjet has exactly the same syntactic distribution as littik/litjet ‘little’ in Saterland Frisian. On Low German, see Lindow et al (1998:191ff), cf. Lücht (2016:77, 241).

To sum up, the t-form of litje ‘small’ may function as the ZERO form of the adjective, which explains its distribution: predicative, adverbial and neuter gender agreement in the attributive construction. The t-forms of other adjectives seem to be restricted to neuter gender agreement in the attributive construction, without being used in predicative and adverbial constructions, so they are not equivalent to the ZERO form of the adjective in general. In this respect, litjet ‘little’ is different, since the t-form is also used in adverbial and predicative function.

The analysis above also explains that a –t may occasionally be found to mark a superlative adjective in an attributive construction, as in the example below:

Superlatives normally have an intrinsic schwa. Adding a –t brings them in line again with other adjectives making neuter gender agreement visible. Compare also the following:

Here there is also gender agreement on the adjective, expressed traditionally, by means of the ZERO form of the adjective. All this should be further investigated, from a bilingual grammatical perspective.