This strong feeling against such actions is the product of a long tradition in Jewish law. The Talmud (b. Gittin 88b) denounces the resort to gentile courts. The Takkanot of the various medieval Jewish communities forbade Jews to resort to gentile courts. This tradition is recorded in vigorous language in the Shulhan Arukh, Hoshen Mishpat 26:1: "Whoever brings his case before the gentile courts is a wicked man, whose action amounts to blasphemy and violence against the Law of Moses, our teacher."
Of course that does not mean that Jews in the past never had recourse to the civil courts. There were circumstances when there was no other way to obtain their rights. If, for example, a debtor was influential and stubborn and refused to be sued in the Jewish courts, he could be sued in the civil courts (usually with the creditor getting express permission from the Jewish authorities). ( Hoshen Mishpat 26: 2, 4, Isserles.) This procedure, as a last resort, is valid because gentile courts may (according to Jewish law) deal with matters of business debts. This limited validity is acknowledged by Jewish law because the "children of Noah" are understood to have been commanded to maintain courts dealing with civil law (dinei mommonot). (Cf. b. Gittin 9a-b.)
If the building pledges discussed in our question are to be considered merely as notes of debt, then, if there is no other way to collect them, it would be permissible to bring them to the civil courts for collection. But surely they are not precisely of the same nature as a business debt. They are rather what the law calls sh'tar matana, a document of gift ( Hoshen Mishpat 68:1). Jewish documents of gift cannot legally (in the eyes of Jewish law) be dealt with by the non-Jewish courts ( Hoshen Mishpat 68:1).
In Jewish law itself, such pledges as certificates of gift are valid, legal documents. If, for example, Jewish law still had the executive authority which it possessed in past centuries, these pledges could be collected by force. The building pledges are equivalent to charity gifts, in general, and are deemed collectible even if the maker of the pledge changes his mind. The law is that the members of the Jewish community may compel each other to give charity (kofin, Yoreh Deah 256:5).
To give zedakah is considered an inescapable religious obligation (chova) which even the poor must fulfill ( Yoreh Deah 248:1). In fact, a promise made to give zedakah has the sacred status of a religious vow (neder, Yoreh Deah 257:3) and, therefore, must be fulfilled without delay.