Short answer. Possibly. Article 1602 presumes a sale with right to repurchase is really an equitable mortgage when the seller binds himself to keep paying the taxes on the property sold. Continuing to shoulder the taxes after supposedly selling the property is one of the circumstances the law treats as suspicious.
What the law says
When the vendor binds himself to pay the taxes on the thing sold
Civil Code, Article 1602 — When a Sale Is Really a Mortgage. Read the full provision →
What the law says
In any other case where it may be fairly inferred that the real intention of the parties is that the transaction shall secure the payment of a debt or the performance of any other obligation.
Civil Code, Article 1602 — When a Sale Is Really a Mortgage. Read the full provision →
Paying the taxes yourself is one of the listed triggers
Article 1602 lists specific facts that, on their own, are enough to presume a sale with right to repurchase is actually an equitable mortgage, and your situation matches one directly: the presumption arises when the vendor binds himself to pay the taxes on the thing sold. If your agreement obligated you, the supposed seller, to keep paying real property taxes on land you no longer own on paper, that arrangement is exactly what this provision was written to catch.
Why this points away from a genuine sale
In an ordinary, completed sale, the burden of paying property taxes shifts to the new owner, because ownership and its accompanying obligations pass together. A seller who remains contractually bound to pay those taxes after the supposed transfer looks like someone who never actually gave up ownership in substance, only in form, while a buyer who does not bear that ordinary cost of ownership looks more like a lender holding the property as security than like a true purchaser.
It fits the broader catch-all as well
Beyond the specific tax provision, Article 1602 also allows the presumption to arise in any other case where it may be fairly inferred that the real intention of the parties is that the transaction shall secure the payment of a debt or the performance of any other obligation. Continuing to pay taxes is one concrete piece of evidence a court can weigh, together with anything else about the arrangement, in deciding whether the parties genuinely intended a sale or were really just securing a debt.
What this means for your transaction
Because you remained obligated to pay the property's taxes after the sale, you have a real basis to argue the deal was, in substance, an equitable mortgage rather than a true sale with right to repurchase, meaning you may still be considered the owner subject to a debt rather than someone who genuinely transferred title. Other facts about the transaction, such as the price paid or who kept possession, would also be relevant to how strong that argument is.