The important part is not the wording itself as much as the intention of those words. In this case, both phrasing styles result in the end up Jewish spiritual power. This is the key point.
With past tense, you assume that the action has just happened as a result of your energy. With present tense, you assume that the action is happening and then finishing basically at the same time. For example, if someone is "permanently losing power" this spells out the same situation as someone who has lost their power.
Affirmations are guides for our intentions. Affirmations themselves do not break the working, unless they fail to guide what you are attempting to accomplish. This can be a problem if you use other people's affirmations, so take the time to understand what the actual goal is supposed to be.
