Or unreasonable delay.

The translation of "amparo" has been endlessly debated and the general consensus is to leave it in Spanish; it is common to refer in English to an action for amparo or amparo action, or amparo proceedings, etc. The basic idea is an appeal for protection or redress of fundamental/constitutional rights when these have allegedly been infringed, and a parenthetical explanation to that effect could be included if it's thought necessary. It exists all over the Spanish-speaking world, though it doesn't work in exactly the same way in every country. This has been addressed here many times in the past, as a glossary search reveals.

But on "mora", this has nothing to do with arrears. By no stretch of the imagination could late payment of a debt be described as an infringement of fundamental rights. The meaning is delay, specifically undue or unreasonable delay in judicial or administrative action by the authorities: citizens have a fundamental right not to be subjected to unreasonable delay in legal or administrative proceedings affecting them. As the old saying goes, justice delayed is justice denied.

I suspect we may be dealing with Argentina here, but I don't think that makes a difference. The following source, an article on "Amparo por mora" by Juan Marcelo Gavaldá, is from Argentina but its explanations are applicable to other countries.

"el amparo por mora, figura que [...] resulta ser un instrumento eficaz para la salvaguarda de los derechos de los particulares frente a una administración que se demora más del tiempo establecido para expedirse sobre las solicitudes que se le presentan.
El término mora ha sido definido por la Real Academia Española como la dilación o tardanza en cumplir una obligación."
https://www.gordillo.com/pdf_unamirada/14gavalda.pdf

As an illustration of the concept, see this case from Spain:

"Spain – Constitutional Court, 11 May 2015, Appeal for the constitutional redress of the fundamental rights of the individual (Recurso de amparo) 4521-2009
[...]
A span of more than three-years between the filing of the appeal against the expulsion order and the original scheduling of the initial oral hearing of such appeal violated a plaintiff’s right to a trial without undue delays,"
http://www.asylumlawdatabase.eu/en/case-law/spain-–-constitu...