**Step 1: Identify the relevant industry**
TERNA S.p.A. is the Italian electricity transmission grid operator. According to the provided sector descriptions, electricity national transmission falls under the "Regulated Utilities" sector. Therefore, we will apply the Regulated Utilities methodology.

**Step 2: Estimate Adjusted Debt**
Based on the S&P baseline formula for Regulated Utilities:
Adjusted_Debt = (reported_debt + leases + pension_deficit + guarantees + hybrid_debt_portion + other_debt_like_items) - eligible_cash

- **Reported Debt:** We sum the short-term and long-term borrowings plus the current portion of long-term borrowings.
  Short-term Borrowings (2023-01-01) = 444,100,000 EUR
  Current Portion of Long-term Borrowings (2023-01-01) = 1,909,300,000 EUR
  Long-term Borrowings (2023-01-01) = 8,416,700,000 EUR
  Reported Debt = 444,100,000 + 1,909,300,000 + 8,416,700,000 = 10,770,100,000 EUR

- **Leases:** No lease liabilities are explicitly reported in the balance sheet facts, so we assume 0 EUR.

- **Pension Deficit:** We look at the net pension position. 
  Noncurrent Provisions for Employee Benefits = 48,400,000 EUR
  There are no reported pension assets. Since the pension is fully provided for as a liability (and typically underfunded), we treat the provision as a deficit. 
  Pension Deficit = 48,400,000 EUR

- **Guarantees:** 0 EUR (Not reported).

- **Hybrid Debt Portion:** S&P typically treats hybrid instruments as 50% equity/50% debt if they meet certain criteria (subordination, permanence, etc.). The company lists "Capital Instruments Bonds Hybrid Perpetual" in equity worth 989,000,000 EUR. 
  Hybrid Debt Portion = 989,000,000 EUR * 50% = 494,500,000 EUR

- **Other debt-like items:** 0 EUR (Not explicitly reported).

- **Eligible Cash:** Cash and Cash Equivalents (2023-01-01) = 2,155,100,000 EUR.

Adjusted_Debt = 10,770,100,000 + 0 + 48,400,000 + 0 + 494,500,000 + 0 - 2,155,100,000 = 9,157,900,000 EUR

**Step 3: Estimate Adjusted EBITDA**
Based on the S&P baseline formula:
Adjusted_EBITDA = EBITDA + adjustment_leases + nonrecurring_losses - nonrecurring_gains ± pension_adjustments ± joint_venture_proportional_EBITDA ± other_normalization_adjustments

- **EBITDA:** Reconstructed using Operating Profit + Depreciation & Amortization.
  Profit Loss From Operating Activities (2022) = 1,333,500,000 EUR
  Depreciation Amortisation And Impairment Loss (2022) = 725,700,000 EUR
  EBITDA = 1,333,500,000 + 725,700,000 = 2,059,200,000 EUR

- **Adjustment for Leases:** 0 EUR (No operating lease interest/dep expense identified).

- **Nonrecurring items:** 0 EUR (Not explicitly separable from reported figures, assumed normalized).

- **Pension adjustments:** 0 EUR (No specific corridor adjustments noted).

- **Joint Venture Proportional EBITDA:** 0 EUR (Not determinable from data provided).

- **Other normalization adjustments:** 0 EUR.

Adjusted_EBITDA = 2,059,200,000 EUR

**Step 4: Calculate the Adjusted Debt / Adjusted EBITDA ratio**
Adjusted_Debt / Adjusted_EBITDA = 9,157,900,000 / 2,059,200,000 = 4.4467...

Rounded to two decimal places, the ratio is 4.45.

<answer>4.45</answer>