To determine S&P's credit trend for REDEIA CORPORACION SA from 2021 to 2022, we will estimate the Adjusted EBITDA, FFO, and Adjusted Debt for both years, and then calculate the year-over-year changes in the Leverage (Adjusted Debt / Adjusted EBITDA) and Cash-flow Coverage (FFO / Adjusted Debt) ratios.

**Step 1: Estimate 2021 & 2022 Adjusted EBITDA**
We approximate EBITDA by adding Depreciation and Amortization to the Profit from Operating Activities (EBIT). 
- **2021 Adjusted EBITDA:** 991,970,000 (EBIT) + 522,114,000 (D&A) = **1,514,084,000 EUR**
- **2022 Adjusted EBITDA:** 961,554,000 (EBIT) + 544,992,000 (D&A) = **1,506,546,000 EUR**

**Step 2: Estimate 2021 & 2022 FFO**
Funds From Operations (FFO) is calculated as Adjusted EBITDA minus net cash interest paid and cash taxes paid. 
- **2021 FFO:** 1,514,084,000 (EBITDA) - [121,920,000 - 4,867,000] (Net Cash Interest) - 181,263,000 (Taxes Paid) = **1,215,768,000 EUR**
- **2022 FFO:** 1,506,546,000 (EBITDA) - [123,524,000 - 15,680,000] (Net Cash Interest) - 363,996,000 (Taxes Paid) = **1,034,706,000 EUR**
*(Note: FFO temporarily declined in 2022 primarily due to a substantial one-off tax payment related to the sale of a minority stake in the Reintel subsidiary).*

**Step 3: Estimate 2021 & 2022 Adjusted Debt**
We compute gross debt primarily via Total Financial Liabilities (Current + Noncurrent) and deduct highly liquid assets (Cash & Cash Equivalents + Short-Term Financial Investments at Amortised Cost). S&P typically nets out the latter, as they represent surplus liquid assets.
- **2021 Gross Debt:** 5,953,434,000 (Noncurrent) + 2,144,425,000 (Current) = 8,097,859,000 EUR
- **2021 Eligible Cash:** 1,574,427,000 (Cash) + 25,401,000 (ST Investments) = 1,599,828,000 EUR
- **2021 Adjusted Debt:** 8,097,859,000 - 1,599,828,000 = **6,498,031,000 EUR**

- **2022 Gross Debt:** 5,543,755,000 (Noncurrent) + 1,705,277,000 (Current) = 7,249,032,000 EUR
- **2022 Eligible Cash:** 794,824,000 (Cash) + 752,505,000 (ST Investments) = 1,547,329,000 EUR 
- **2022 Adjusted Debt:** 7,249,032,000 - 1,547,329,000 = **5,701,703,000 EUR**
*(The structural drop in net debt was facilitated by the ~€1B cash proceeds from the Reintel stake sale).*

**Step 4: Calculate Ratios & Evaluate Trend**
- **2021 Leverage (Adj. Debt / Adj. EBITDA):** 6,498,031,000 / 1,514,084,000 = **4.29x**
- **2022 Leverage (Adj. Debt / Adj. EBITDA):** 5,701,703,000 / 1,506,546,000 = **3.78x**
  - *Change in Leverage:* 3.78x - 4.29x = **-0.51x** (A decrease of more than -0.2x indicates an **Improving** signal).

- **2021 Cash-Flow Coverage (FFO / Adj. Debt):** 1,215,768,000 / 6,498,031,000 = **18.7%**
- **2022 Cash-Flow Coverage (FFO / Adj. Debt):** 1,034,706,000 / 5,701,703,000 = **18.1%**
  - *Change in FFO/Debt:* 18.1% - 18.7% = **-0.6% or -0.006** (Well within the [-0.03, +0.03] boundary, meaning this represents a **Stable** signal).

**Conclusion:**
With Leverage displaying a firmly **Improving** trajectory driven by significant debt reduction and Cash-Flow Coverage remaining **Stable** (suppressed mostly by non-recurring one-off asset sale tax payments), the blended trend results in a non-stable directional upgrade.

<answer>Improving</answer>