I think that the literal translation deuda técnica fits perfectly.
Being an IT professional, I didn't know the term, but after reading this definition, I can say that I've experienced it more than once.
Technical debt can be defined as the longer term consequences of poor design decisions
You have to take into account that in software development there is a phase named technical design which is usually translated as diseño técnico (with its namesake documents) and which seems to be the origin of this technical debt
I disagree with @walen, I think that tecnológica is not a adequate in this context.
Let's check the D.R.A.E
- adj. Perteneciente o relativo a la tecnología.
- f. Conjunto de teorías y de técnicas que permiten el aprovechamiento práctico del conocimiento científico.
f. Conjunto de procedimientos y recursos de que se sirve una ciencia o un arte.
f. Pericia o habilidad para usar una técnica.
As you can see, tecnología and técnica may be synonimous. But in IT usually a tecnology identifies a programming language or a bunch of libraries and the tecnical debt is not directly related with that, I think that it has got more to do with how you employ such technology, how you design a solution.