English to Spanish Social Sciences Social Science, Sociology, Ethics, etc. Psychometrics

I'm evaluating a translation into Spanish of a short survey on weight loss. I'm not sure how best to express the response options. Participants are asked, “How certain are you that you could overcome the following barriers?” The response options are "(1) very uncertain, (2) rather uncertain, (3) rather certain, and (4) very certain." Participants are to choose one of those options in response to declarative sentences, such as "I can manage to stick to healthful foods, even if I need a long time to develop the necessary routines" or "I can manage to carry out my exercise intentions, even if I feel depressed."

The suggested translation of the initial question is, "¿Qué tan seguro está de que podría superar las siguientes barreras?" That looks fine to me. But then the suggested translation of the response options is: "(1) Muy incierto, (2) Algo incierto, (3) Algo cierto, (4) Muy cierto.

Dictionary definitions seem to support this translation, but I have two problems with it. First, the initial question uses "seguro," so I would think the response scale should use the same term. Second, it just doesn't sound right to me. "Estoy muy cierto que podré superar esta barrera"? I'm accustomed to hearing "cierto" applied to the veracity of the statement--"Eso es cierto"--rather than to the subjective degree of confidence that the speaker feels about his ability to accomplish a given task. Am I misunderstanding the usage of the term? The translator is a native speaker of Spanish; I am not. I don't want to correct his Spanish unless I'm sure I'm right!

I'm thinking of changing it to Muy inseguro, algo inseguro, algo seguro, muy seguro.

Which do you prefer? Which is more commonly used? Do you have a better suggestion? The translation is proposed for immediate use in Puerto Rico, but a phrase that is understood internationally would be ideal.

Thank you for any help that you can give me.